[Federal Register Volume 64, Number 176 (Monday, September 13, 1999)]
[Rules and Regulations]
[Pages 49548-49634]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-22964]
[[Page 49547]]
_______________________________________________________________________
Part II
Department of Labor
_______________________________________________________________________
Mine Safety and Health Administration
_______________________________________________________________________
30 CFR Parts 56 and 57 et al.
Health Standards for Occupational Noise Exposure; Final Rule
Federal Register / Vol. 64, No. 176 / Monday, September 13, 1999 /
Rules and Regulations
[[Page 49548]]
DEPARTMENT OF LABOR
Mine Safety and Health Administration
30 CFR Parts 56, 57, 62, 70 and 71
RIN 1219-AA53
Health Standards for Occupational Noise Exposure
AGENCY: Mine Safety and Health Administration (MSHA), Labor.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: This final comprehensive rule replaces MSHA's existing
standards for occupational noise exposure in coal mines and metal and
nonmetal mines. The final rule establishes uniform requirements to
protect the Nation's miners from occupational noise-induced hearing
loss. The rule is derived in part from existing MSHA noise standards,
and from the Department of Labor's existing occupational noise exposure
standard for general industry promulgated by the Occupational Safety
and Health Administration (OSHA).
As a result of the Agency's ongoing review of its safety and health
standards, MSHA determined that its existing noise standards, which are
more than twenty years old, do not adequately protect miners from
occupational noise-induced hearing loss. A significant risk to miners
of material impairment of health from workplace exposure to noise over
a working lifetime exists when miners' exposure exceeds an 8-hour time-
weighted average (TWA8) of 85 dBA.
MSHA expects that the final rule will significantly reduce the risk
of material impairment within the mining industry as a whole.
DATES: The final rule is effective September 13, 2000.
FOR FURTHER INFORMATION CONTACT: Carol J. Jones, Acting Director,
Office of Standards, Regulations, and Variances, MSHA, 4015 Wilson
Boulevard, Arlington, VA 22203-1984. Ms. Jones can be reached at
cjones@msha.gov (Internet E-mail), 703/235-1910 (voice), or 703/235-
5551 (fax).
SUPPLEMENTARY INFORMATION:
I. Background
a. Noise-Induced Hearing Loss
Noise is one of the most pervasive health hazards in mining. The
National Institute for Occupational Safety and Health (NIOSH) has
identified noise-induced hearing loss as one of the ten leading work-
related diseases and injuries. Exposure to hazardous sound levels
results in the development of occupational noise-induced hearing loss,
which is distinguishable from hearing loss associated with aging or
with medical conditions. For many years, the risk of acquiring noise-
induced hearing loss was accepted as an inevitable consequence of
mining occupations, in which the use of mechanized equipment often
subjects miners to hazardous noise exposures. But noise-induced hearing
loss can be diagnosed, prevented, and its progress delayed.
Prolonged exposure to noise over a period of years generally causes
permanent damage to the auditory nerve or its sensory components.
Hearing loss is rapid when exposures are over a prolonged period at
high sound levels. Hearing loss may also be gradual, so that the
impairment is not noticed until after a substantial amount of hearing
loss occurs. Noise-induced hearing loss is irreversible. Considerable
safety risks arise because workers with noise-induced hearing loss may
not hear audible warnings and safety signals. In addition, most people
with noise-induced hearing loss have reduced hearing sensitivity to
higher frequencies and lose the ability to discriminate consonants,
making them unable to distinguish among words differing only by one or
more consonants. This impairment jeopardizes the safety of affected
miners as well as the safety of those around them, and, as a result,
general employee health and productivity.
Revising the existing rules to protect miners from noise-induced
hearing loss is necessary because exposure to workplace noise continues
to present a significant risk of material impairment of health to
miners. MSHA estimates that 13.4% of the mining population of the
United States (approximately 13,000 coal miners and 24,000 metal and
nonmetal miners) will develop a material hearing impairment during a
working lifetime under current working conditions. MSHA anticipates
that miners will benefit substantially from the final rule's effect of
improving miner health and lessening the personal and social hardships
of occupational noise-induced hearing loss.
b. Rulemaking Process
MSHA's existing noise standards in metal and nonmetal mines (30 CFR
Secs. 56.5050 and 57.5050) and in coal mines (30 CFR Secs. 70.500-
70.511, and Secs. 71.800-71.805) were originally promulgated in the
early 1970's. They were derived from the Walsh-Healey Public Contracts
Act occupational noise standard, which adopted a permissible exposure
level of 90 dBA, a 5-dB exchange rate, and a 90-dBA threshold. After
considering the recurrent incidence of noise-induced hearing loss among
miners and repeated recommendations from the mining community that MSHA
adopt a single noise standard covering all mines, MSHA published an
Advance Notice of Proposed Rulemaking (ANPRM) (54 FR 50209) on December
4, 1989. In response, the Agency received numerous comments from mine
operators, trade associations, labor groups, equipment manufacturers,
and other interested parties.
After reviewing the comments to the ANPRM, MSHA published a
proposed rule (61 FR 66348) on December 17, 1996. The comment period,
originally scheduled to close on February 18, 1997, was extended to
April 21, 1997 (62 FR 5554), and 6 public hearings were conducted in
Beckley, West Virginia; St. Louis, Missouri; Denver, Colorado; Las
Vegas, Nevada; Atlanta, Georgia; and Washington, D.C. Transcripts of
the proceedings were made available to the public. Supplementary
statements and data were received from interested persons until the
record closed on August 1, 1997.
After the close of the record, NIOSH sent MSHA a report entitled,
``Prevalence of Hearing Loss For Noise-Exposed Metal/Nonmetal Miners.''
On December 16, 1997, MSHA published a notice (62 FR 65777) announcing
that the report was available and had been entered into the rulemaking
record. Then, on December 23, 1997, MSHA published a follow-up notice
(62 FR 67013) inviting interested persons to comment on the NIOSH
report, with the comment period closing on February 23, 1998.
Early commenters on the proposal expressed concern that the spirit
of section 103(c) of the Federal Mine Safety and Health Act of 1977
(Mine Act) was not being met. Section 103(c) requires that miners or
their representatives be allowed to observe any monitoring or measuring
of hazards in their workplaces and to have access to monitoring
records. Proposed Sec. 62.120(f) contained a provision requiring
operators to establish a system of monitoring for effectively
evaluating each miner's noise exposure, but did not require that miners
be allowed to observe.
In response, on December 31, 1997, MSHA published a notice (62 FR
68468) supplementing its proposed rule with proposed Sec. 62.120(g),
asked for comments, and scheduled a public hearing. The comment period
for the supplement closed on February 17, and a public hearing was held
in
[[Page 49549]]
Washington, DC on March 10. The post-hearing comment period and
rulemaking record closed on April 9, 1998.
On May 26, 1998, MSHA published a notice (63 FR 28496) announcing
its preliminary determination of no significant environmental impact;
requesting comments; and reopening the rulemaking record for the
limited purpose of receiving these comments.
The agency received many comments on the proposed noise rule,
including the supplemental proposed rule on observation of monitoring.
The agency received a total of 182 written and electronic comments. In
addition, 57 speakers provided verbal comments at the public hearings.
Comments were received from various entities including mine operators,
industry trade associations, such as the National Mining Association,
National Stone Association, American Iron and Steel Institute and
American Portland Cement Alliance; organized labor groups, such as the
United Mine Workers of America and the United Steelworkers of America;
noise equipment manufacturers; the American Industrial Hygiene
Association; the National Hearing Conservation Association; the
Acoustical Society of America; colleges and universities; and other
Federal agencies, such as NIOSH and the U.S. Small Business
Administration.
c. Current Standards
MSHA's existing maximum noise exposure levels for metal and
nonmetal mines (30 CFR 56/57.5050) and for coal mines (30 CFR 70.500
through 70.511 and 71.800 through 71.805), were derived from the Walsh-
Healey Public Contracts Act occupational noise standard. The standards
adopted a permissible exposure level of 90 dBA as an eight-hour time
weighted average and a 5-dB exchange rate.
MSHA's existing metal and nonmetal noise standards require the use
of feasible engineering or administrative controls when a miner's noise
exposure exceeds the permissible exposure level. Hearing protectors are
also required if the exposure cannot be reduced to within the
permissible exposure level. The existing metal and nonmetal standards
do not require the mine operator to post the procedures for any
administrative controls used, to conduct specific training, or to
enroll miners in hearing conservation programs.
MSHA's existing practices for coal mines are different from those
for metal and nonmetal mines due to differences in the circumstances
under which the Agency is authorized to issue citations. In metal and
nonmetal mines, a citation is issued based exclusively on the exposure
measurement. In coal mines, a citation is not issued if appropriate
hearing protectors are being worn. Moreover, when a coal mine operator
receives a citation for noise exposure exceeding the permissible
exposure level, the operator is required to promptly institute
administrative and/or engineering controls to assure compliance. In
addition, within 60 days of receiving the citation, a coal mine
operator is required to submit a plan to MSHA for the administration of
a continuing, effective hearing conservation program.
The Federal Mine Safety and Health Review Commission (Commission)
has addressed the ``feasibility'' of noise controls regarding the
existing standards. In determining technological feasibility, the
Commission has held that a control is deemed achievable if through
reasonable application of existing products, devices, or work methods
with human skills and abilities, a workable engineering control can be
applied to the noise source. The control does not have to be ``off-the-
shelf;'' but it must have a realistic basis in present technical
capabilities. In determining economic feasibility, the Commission has
held that MSHA must assess whether the costs of the control are
disproportionate to the ``expected benefits'', and whether the costs
are so great that it is irrational to require its use to achieve those
results. The Commission has expressly stated that cost-benefit analysis
is unnecessary in order to determine whether a noise control is
required. According to the Commission, an engineering control may be
feasible even though it fails to reduce exposure to permissible levels
contained in the standard, as long as there is a significant reduction
in exposure. In Todilto Exploration and Development Corporation, 5
FMSHRC 1894 (1983), the Commission accepted the Agency's determination
that a 3 dBA reduction is significant.
MSHA has interpreted the ``expected benefits'' to be the amount of
noise reduction achievable by the control. MSHA generally considers a
reduction of 3 dBA or more to be a significant reduction of the sound
level because it represents at least a 50% reduction in sound energy.
Consequently, a control that achieves relatively little noise reduction
at a high cost could be viewed as not meeting the Commission s test of
economic feasibility.
MSHA estimates that the costs attributable to the final rule
requirement to use engineering and administrative controls would be
significantly offset by the paperwork savings the coal mining industry
will accrue. The existing costly, paperwork-intensive requirements for
biannual coal miner noise exposure surveys, supplemental noise surveys,
calibration reports, survey reports, and survey certifications are
eliminated by the final rule. Rather, the final rule has a flexible
requirement for mine operators to establish a monitoring program that
effectively evaluates miner exposures.
II. Final Rule
a. General Requirements Applicable to All Mines
The following summarizes general requirements for all mines in the
final rule although, the rule and this preamble should be consulted for
details. A mine operator must establish a system of monitoring which
evaluates each miner's noise exposure. In addition, the mine operator
must give prior notice and provide affected miners and their
representatives with an opportunity to observe the monitoring. When an
exposure equals or exceeds the action level, exceeds the permissible
exposure level, or exceeds the dual hearing protection level, the mine
operator must notify a miner of his or her exposure. A copy of the
notification must be kept for the duration of the affected miner's
exposure at or above the action level and for at least 6 months
thereafter.
If a miner's noise exposure is less than the action level, no
action is required by the mine operator. If the miner's exposure equals
or exceeds the action level, but does not exceed the permissible
exposure level, the operator must enroll the miner in a hearing
conservation program which includes a system of monitoring, voluntary
use of operator-provided hearing protectors, voluntary audiometric
testing, training, and record keeping. If a miner's exposure exceeds
the permissible exposure level, the operator must use or continue to
use all feasible engineering and administrative controls to reduce
exposure to the permissible exposure level, enroll the miner in a
hearing conservation program including ensuring the use of operator-
provided hearing protectors, post administrative controls and provide a
copy to the affected miner; and must never permit a miner to be exposed
to sound levels exceeding 115 dBA. If a miner's exposure exceeds the
dual hearing protection level, the operator must enroll the miner in a
hearing conservation program, continue to meet all the requirements for
exposures above the permissible exposure level, and
[[Page 49550]]
ensure the concurrent use of an earplug and earmuff.
b. Major Features of the Final Rule
Consistent with OSHA's noise exposure standard, MSHA has adopted
the existing permissible exposure level of 90 dBA as an 8-hour time-
weighted average (TWA8). The final rule, however, requires
the use of all feasible engineering and administrative controls to
reduce a miner's noise exposure to the permissible exposure level. Such
controls may be used separately or in combination. When controls do not
reduce exposure to the permissible exposure level, miners must be
provided hearing protectors and mine operators are required to ensure
that the miners use them.
The final rule also addresses a currently recognized hazard that is
not covered by existing standards: noise exposures at or above a
TWA8 of 85 dBA but below the permissible exposure level.
Exposure at a TWA8 of 85 dBA is termed the ``action level,''
and, under the final rule, mine operators are required to enroll miners
exposed at or above the action level in a hearing conservation program
consisting of exposure monitoring, the use of hearing protectors,
audiometric testing, training, and recordkeeping.
The final rule has been revised from the proposal in several
respects, which makes it more consistent with existing OSHA
regulations:
MSHA had proposed that all sound levels between 80 dBA and 130 dBA
be included in determining exposure for both the action level and
permissible exposure level. Based on comments received, the final rule
requires inclusion of sound levels between 90 dBA and at least 140 dBA
for determining exposure with respect to the permissible exposure
level. The final rule adopts the proposed inclusion of sound levels
from 80 dBA to at least 130 dBA for determining exposure with respect
to the action level.
In response to the proposed definition of a hearing conservation
program, commenters suggested that, for the sake of consistency, the
final rule adopt the existing definition included in the OSHA noise
standard. MSHA agrees and has revised the final rule to incorporate all
relevant elements of a hearing conservation program under this
definition.
The proposed rule would have required mine operators to ensure that
miners participate in an audiometric testing program if their noise
exposures were above the permissible exposure level. In response to
commenters, the final rule requires only that mine operators offer
audiometric testing, leaving it to the miner to decide whether to
participate in the testing program.
The proposed rule would have required that mine operators ensure
that miners were not exposed to workplace noise during a 14-hour quiet
period required before a baseline audiogram is taken. In addition, the
use of hearing protectors would not have been permitted as a substitute
for the quiet period. Many commenters suggested that prohibiting the
use of hearing protectors to meet the quiet period requirement was not
practical, because many miners work 12-hour shifts and that OSHA's
noise standard allows hearing protection to be used during the quiet
period. The final rule permits the use of hearing protectors during the
quiet period.
The proposed rule would have required a mine operator, upon
termination of a miner's employment, to provide the miner with a copy
of the records required under part 62. Commenters overwhelmingly
supported giving copies of records only to those miners who request
them. In response to comments, the proposed provision was not adopted
in the final rule, and the final rule instead requires that mine
operators provide copies of records to miners upon request.
The final rule departs from the OSHA noise standard in several
respects:
The final rule adopts the proposed ``dual hearing protection
level'' at a TWA8 of 105 dBA. This requirement for dual
hearing protection is supported by research showing that greater noise
reduction results from the use of both earplugs and earmuffs than from
either type of hearing protector alone. Accordingly, mine operators
must provide and require the use of both an earplug and an earmuff at a
TWA8 of 105 dBA.
The final rule does not include detailed, technical procedures and
criteria for conducting audiometric testing. Rather, the rule is
performance-oriented, requiring only that audiometric testing be
conducted in accordance with scientifically validated procedures, such
as those in OSHA's noise standard.
Nor does the final rule require determining the adequacy of hearing
protectors. Although OSHA's noise standard includes such information in
its mandatory Appendix B, MSHA's research on mining applications
indicates that hearing protectors provide less reduction than their
ratings suggest and that the reduction achieved is highly variable.
These two factors prevent accurate prediction of the effectiveness of
hearing protectors for a given individual. However, MSHA recognizes
that in some environments it may not be feasible to reduce miners'
noise exposures to the permissible exposure level with the use of
engineering or administrative controls. In these circumstances, the
interim use of personal hearing protectors may offer the best
protection until controls become feasible and can be implemented.
The final rule is consistent with Executive Order 12866, the
Regulatory Flexibility Act, the Small Business Regulatory Enforcement
Fairness Act (SBREFA), the National Environmental Policy Act (NEPA),
the Paperwork Reduction Act, the Unfunded Mandates Reform Act, and the
Mine Act. MSHA estimates that metal and nonmetal mines with fewer than
20 miners would incur an average cost increase of about $460 annually.
Coal mines with fewer than 20 miners would have an average cost
increase of about $400, reflecting the elimination of the numerous
survey and paperwork requirements in the current noise rules for the
coal sector.
In accordance with the SBREFA Amendments to the Regulatory
Flexibility Act, MSHA has taken steps to minimize the compliance burden
on small mines. The effective date of the final rule, one year after
promulgation, provides time for small mines to achieve compliance. In
addition, MSHA is mailing a copy of the final rule to each mine
operator, which benefits small mine operators.
MSHA anticipates that the mining community will benefit
substantially from the final rule. The primary benefit will be a
sizable reduction, by as much as two-thirds, in the incidence of
occupational hearing impairment among miners. The final rule will also
serve to mitigate the progression of hearing loss in working miners and
preserve the health and quality of life of miners newly entering the
industry.
Two charts compare key features of the final standard to MSHA's
existing standards. Note that entries in the charts and the discussions
in the preamble reflect legal and/or policy interpretations that would
not be apparent from the text of the standards. Other parts of this
preamble should be consulted for details.
[[Page 49551]]
Chart 1: General Requirements
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Existing metal and
Noise level Final rule nonmetal rules Existing coal rules
----------------------------------------------------------------------------------------------------------------
At or above a TWA8 of 85 dBA Enroll miner in HCP which No requirements....... No requirements.
(action level). includes requirements for
training, monitoring,
recordkeeping, voluntary
hearing tests, voluntary
use of operator-provided
HP in most cases, but use
of HP is mandatory in
particular instances.
Above a TWA8 of 90 dBA (PEL)....... Use or continue to use all Use all feasible Use all feasible
feasible engineering and engineering or engineering and/or
administrative controls to administrative administrative
reduce exposure to PEL; controls and provide controls, but can
enroll miner in an HCP HP if noise level first reduce exposure
including ensuring use of cannot be lowered to by rated value of HP
operator-provided HP, post PEL. minus 7 unless cited
administrative controls for failure to
and provide copy to require HP use; also
affected miner, never must enroll miners in
permit miner to be exposed HCP if cited.
to sound levels exceeding
115 dBA.
At or above 105 dBA (dual hearing Ensure concurrent use of Limited requirement N/A
protection level). earplug and earmuff type for dual HPs.
HPs in addition to above
requirements for the
action level and PEL.
----------------------------------------------------------------------------------------------------------------
Abbreviations: HP (hearing protector), HCP (hearing conservation program), TWA8 (eight-hour time-weighted
average), dBA (decibel, A-weighted), PEL (permissible exposure level); Hz (hertz), and n/a (not applicable).
Comparison Chart 2: General Features
----------------------------------------------------------------------------------------------------------------
Existing metal and
Feature Final rule nonmetal rules Existing coal rules
----------------------------------------------------------------------------------------------------------------
Monitoring......................... Operator must establish an No requirement on mine Mine operator required
effective system of operator. to conduct periodic
monitoring noise exposure. monitoring.
Notification of exposure........... Operator must notify miner Not required.......... Not required.
of certain exposures.
Dual Threshold (lowest sound level 85 dBA for action level and 90 dBA for PEL........ 90 dBA for PEL.
counted). 90 dBA for PEL.
Exchange rate...................... 5 dB....................... 5 dB.................. 5 dB.
Training........................... Specific training Part 48............... Part 48.
requirements.
Quiet period prior to audiometric 14 hours for baseline N/A................... N/A.
examination. audiogram and use of HP
permitted.
Standard Threshold shift........... Average of 10 dB at 2000, N/A................... N/A.
3000, and 4000 Hz in
either ear.
Reportable hearing loss............ Average of 25 dB at 2000, Reporting required but Reporting required but
3000, and 4000 Hz in level was undefined. level was undefined.
either ear.
Employee access to records......... Available upon request..... N/A................... N/A.
----------------------------------------------------------------------------------------------------------------
Abbreviations: HP (hearing protector), dBA (decibel, A-weighted), PEL (permissible exposure limit); Hz (hertz),
n/a (not applicable).
III. Paperwork Reduction Act of 1995
The information collection requirements contained in this final
rule have been submitted to the Office of Management and Budget (OMB)
for review under the Paperwork Reduction Act of 1995 (44 U.S.C. 3501-
3520), as implemented by OMB in regulations at 5 CFR part 1320. The
Paperwork Reduction Act of 1995 (PRA 95) defines collection of
information as ``the obtaining, causing to be obtained, soliciting, or
requiring the disclosure to third parties or the public of facts or
opinions by or for an agency regardless of form or format.'' (44 U.S.C.
3502(3)(A)). Under PRA 95, no person may be required to respond to, or
may be subjected to a penalty for failure to comply with, these
information collection requirements until they have been approved and
MSHA has announced the assigned OMB control number. The OMB control
number, when assigned, will be announced by separate notice in the
Federal Register. In accordance with Sec. 1320.11(h) of the
implementing regulations, OMB has 60 days from today's publication date
in which to approve, disapprove, or instruct MSHA to make a change to
the information collection requirements in this final rule.
Recordkeeping requirements in the final rule are found in
Secs. 62.110, 62.130, 62.170, 62.171, 62.172, 62.173, 62.174, 62.175,
62.180, and 62.190.
MSHA received comments both supporting and opposing the proposed
information collection requirements. MSHA has reviewed these comments.
Several commenters questioned MSHA's estimates of the paperwork burden
reduction of the noise rule. Two commenters noted that the February
1984 Program Information Bulletin 84-1C ``eliminated virtually all
paperwork requirements for operators'' and that the ``paperwork
involves one letter and two 32 cent stamps per year per coal
operator.'' The February 1984 Program Information Bulletin eliminated
the requirement for the completion and submission to MSHA of a Coal
Mine Noise Data Report Form when operator noise exposure surveys are
found to be within compliance. The Program Information Bulletin
retained the requirement that a written and signed statement
(certification) be submitted to MSHA that the required surveys were
made and that the surveys show compliance. The Program Information
Bulletin did not drop the requirement for noise surveys to be
conducted, exclude the requirement for supplemental noise surveys for
exposures at or above the permissible exposure level (and a submission
of them), or eliminate the requirement of
[[Page 49552]]
surveying all miners and retaining a record.
In addition, as MSHA stated in the proposal, there are labor and
equipment costs related to performing the surveys twice a year,
completing survey reports and certifications, doing calibration reports
annually, and collecting a noise monitoring record for all coal miners.
Under PRA 95, all activities related to the generation of a paperwork
item must be considered when calculating the costs and burden of
paperwork tasks. For these reasons, MSHA's estimates in the final rule
are consistent with the requirements of PRA 95.
Other commenters stated that they will still have to conduct
surveys, retain survey records, conduct training and audiometric
testing, and implement engineering and administrative controls to
demonstrate compliance. The existing standards require coal mine
operators to perform semiannual monitoring for each miner. Under the
final rule, mine operators must establish a system of monitoring that
evaluates each miner's noise exposure sufficiently to determine
continuing compliance with this part. However, under the final rule
mine operators may use their own monitoring records as well as the
Agency's data from inspector sampling to determine compliance.
Some commenters stated that the performance-based system of
monitoring may result in increased monitoring. MSHA anticipates that a
number of mine operators will use some form of representative sampling
within job classes or work areas to minimize costs related to dose
determination. In addition, large operators who use the same equipment
on more than one shift may conduct monitoring on a single shift to
determine miner exposures, provided that the circumstances are similar.
The Agency published a supplemental proposal that would give
affected miners and their representatives the right to observe operator
monitoring. MSHA estimated that the time required for observation of
monitoring would take about 2 hours annually at small mines and about 5
hours annually at large mines. Several commenters questioned the
Agency's estimates. One commenter questioned the Agency's estimate of 5
hours for a large mine. The commenter believed that for a mine which
employed 1,500 workers, 12,000 hours will be spent on noise monitoring
(1,500 workers * an 8 hour workday). Under the final rule, mine
operators will need to determine miners' exposure; this may be achieved
in a number of ways including the use of existing monitoring records
(particularly for coal mine operators), review of MSHA sampling
records, or by the use of representative sampling. Since mine operators
are not specifically required by the final rule to monitor each
employee but may use a more flexible approach, MSHA anticipates that
its estimates of an average of 2 hours and 5 hours annually at small
and large mines respectively (reflecting 30 minute monitoring for each
of four miners in a small mine and ten miners in a large mine) are
reasonable.
Another commenter questioned if there will be an observation time
limit and also believed that MSHA's estimate of 5 hours annually was
too low. Also, a commenter questioned MSHA's estimates of lost
production, the length of time needed for observation, and MSHA's
average time estimates per small mine and per large mine. A commenter
also believed that the total estimated annual information collection
burden was low. With the exception of the one commenter who provided
the estimate of 12,000 hours annually to observe monitoring, none
provided data to support their statements.
At the public hearing, several commenters testified that they
considered MSHA's time estimates and photocopy cost estimates high. In
particular, they believed that the time to give instructions to the
secretary were excessive. Further, they stated MSHA's estimates for the
length of time to perform typing and posting were too high. Other
commenters stated that the bulk of the paperwork would be completed by
safety professionals and industrial hygienists as opposed to clerical
workers. Based upon a review of all the comments and MSHA's experience,
the Agency believes the estimates in the final rule are reasonable.
The proposed rule would have required mine operators to obtain from
the physician, audiologist, or qualified technician who conducts an
audiometric test a certification that each test was conducted in
accordance with scientifically validated procedures. Commenters stated
that requiring mine operators to obtain a certification for each
individual audiogram was unduly burdensome. The Agency agrees and the
proposed certification requirement has not been adopted in the final
rule. Under the final rule, evidence is simply required that the
audiograms were conducted in accordance with scientifically validated
procedures. For example, the evidence may consist of a single statement
from the audiometric test provider or a single billing record that
indicates that required procedures were followed for a number of
audiograms.
The proposed rule would have required mine operators to provide
miners with a copy of all their records relating to this standard when
those miners terminate employment. Commenters stated that this was an
unnecessary requirement which generated too much paper and that miners
may not even want a copy of the records. In response, the final rule
requires mine operators to provide copies of records to a miner if the
miner requests such records.
Numerous commenters stated that records should not have to be
retained at the mine site. MSHA agrees and the final rule provides that
records are not required to be maintained at the mine site, and
therefore can be electronically filed in a central location, so long as
the records are made available to the authorized representative of the
Secretary upon request within a reasonable time, in most cases one day.
Although the final rule does not require backing up the data, some
means are necessary to ensure that electronically stored information is
not compromised or lost. MSHA encourages mine operators who store
records electronically to provide a mechanism that will allow the
continued storage and retrieval of records in the year 2000.
MSHA solicited comment on what actions would be required, if any,
to facilitate the maintenance of records in electronic form by those
mine operators who desire to do so, while ensuring access in accordance
with these requirements. The Agency received several comments
supporting electronic storage of records, but no specifics regarding
actions required to facilitate the maintenance of the records in
electronic form. In revising the requirements from those that appeared
in the proposed rule, MSHA has evaluated the necessity and usefulness
of the collection of information; reevaluated MSHA's estimate of the
information collection burden, including the validity of the underlying
methodology and assumptions; and minimized the information collection
burden on respondents to the greatest extent possible. The following
charts provide, by section, the paperwork requirements for Year 1 and
for each succeeding year, respectively.
[[Page 49553]]
Table 1.--Summary of Net Information Collection Burden Hours in Year 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
Coal mines M/NM mines
Section Paperwork requirements and associated ---------------------------------------------------- Total
tasks Small Large Small Large
--------------------------------------------------------------------------------------------------------------------------------------------------------
62.110 to 62.130.............................. Evaluate noise exposure; notify miners, (7,988) (50,666) 14,605 12,579 (31,471)
prepare, post, and distribute
administrative controls; and permit
observation of monitoring.
62.170........................................ Perform audiograms; and notify miners 940 4,181 3,577 5,271 13,969
to appear for testing and of need to
avoid high noise levels.
62.171........................................ Compile an audiometric test record; and 1,021 4,616 3,882 5,820 15,339
obtain evidence.
62.172........................................ Provide information and audiometric 1,413 4,374 5,474 5,513 16,774
test record; and perform audiometric
retests.
62.173........................................ Perform otological evaluations; and 7 27 29 34 98
provide information and notice.
62.174........................................ Prepare a retraining certification; and 105 334 407 420 1,266
review effectiveness of engineering
and administrative controls.
62.175........................................ Inform miners of test results and tSTS. 1,038 4,623 3,950 5,829 15,440
62.180........................................ Prepare and file a training 1,280 4,165 4,957 5,180 15,581
certificate..
62.190........................................ Provide access to, and transfer, 244 303 1,027 915 2,489
records.
----------------------------------------------------------------
Total................................... ..................................... (1,941) (28,045) 37,909 41,561 49,484
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table 2.--Summary of Net Information Collection Burden Hours for After Year 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
Coal mines M/NM mines
Section Paperwork requirements and associated ---------------------------------------------------- Total
tasks Small Large Small Large
--------------------------------------------------------------------------------------------------------------------------------------------------------
62.110 to 62.130.............................. Evaluate noise exposure; notify miners, (8,532) (48,006) 6,595 3,567 (46,376)
prepare, post, and distribute
administrative controls; and permit
observation of monitoring.
62.171........................................ Compile an audiometric test record; and 153 692 582 873 2,301
obtain evidence.
62.172........................................ Provide information and audiometric 212 656 821 827 2,516
test record; and perform audiometric
retests.
62.173........................................ Perform otological evaluations; and 1 4 4 5 15
provide information and notice.
62.174........................................ Prepare a retraining certification; and 16 53 62 67 198
review effectiveness of engineering
and administrative controls.
62.175........................................ Inform miners of test results and STS.. 156 694 593 874 2,316
----------------------------------------------------------------
Total................................... ....................................... (7,994) (45,907) 8,658 6,213 (39,029)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Executive Order 12866 and Regulatory Flexibility Analysis
In accordance with Executive Order 12866, MSHA has prepared a final
analysis of the estimated costs and benefits associated with the
revisions of the noise standards for coal and metal and nonmetal mines.
The final Regulatory Economic Analysis containing this analysis is
available from MSHA. The final rule will cost approximately $8.7
million annually and will prevent or contribute to the prevention of
approximately 595 hearing impairment cases annually. The benefits are
expressed in terms of cases of hearing impairment that can be avoided
and have not been monetized. Although the Agency has attempted to
quantify the benefits, it believes that monetization of these benefits
would be difficult and inappropriate.
Based upon the economic analysis, MSHA has determined that this
rule is not an economically significant regulatory action pursuant to
section 3(f)(1) of Executive Order 12866. The Agency does consider this
rulemaking significant under section 3(f)(4) of the Executive Order for
other reasons, and has so designated the rule in its annual agenda.
Regulatory Flexibility Certification
In accordance with section 605 of the Regulatory Flexibility Act,
the Mine Safety and Health Administration certifies that the final
noise rule does not have a significant economic impact on a substantial
number of small entities. Traditionally, MSHA considers small mines to
be mines with fewer than 20 employees. Under the Regulatory Flexibility
Act, MSHA must use the SBA definition for a small mine of 500 employees
or fewer or, after consultation with the SBA Office of Advocacy,
establish an alternative definition in the Federal Register for notice
and comment. The alternative definition could be the Agency's
traditional definition of ``fewer than 20 miners'' or some other
definition. As reflected in the certification, MSHA analyzed the costs
of this final rule for small and large mines using both the traditional
Agency definition and SBA's definition, as required by the Regulatory
Flexibility Act, of a small mine. No small governmental jurisdictions
or
[[Page 49554]]
nonprofit organizations are adversely affected.
Under the Small Business Regulatory Enforcement Fairness Act
(SBREFA) amendments to the Regulatory Flexibility Act, MSHA must
include in the final rule a factual basis for this certification. The
Agency must also publish the regulatory flexibility certification
statement in the Federal Register, along with the factual basis,
followed by an opportunity for the public to comment. The Agency has
consulted with the Small Business Administration (SBA) Office of
Advocacy and believes that this analysis provides a reasonable basis
for the certification in this case.
In the proposal, MSHA specifically solicited comments on the
Agency's regulatory flexibility certification statement, including cost
estimates and data sources. To facilitate public participation in the
rulemaking process, MSHA mailed a copy of the proposal and will mail a
copy of the final rule, including the preamble and regulatory
flexibility certification statement, to every mine operator and miners'
representative.
Factual Basis for Certification
General Approach
The Agency's analysis of impacts on ``small entities'' and ``small
mines'' begins with a ``screening'' analysis. The screening compares
the estimated compliance costs of the final rule for small mine
operators in the affected sector to the estimated revenues for that
sector. When estimated compliance costs are less than 1 percent of
estimated revenues (for the size categories considered), the Agency
believes it is generally appropriate to conclude that there is no
significant impact on a substantial number of small entities. When
estimated compliance costs approach or exceed 1 percent of revenue, it
tends to indicate that further analysis may be warranted.
Derivation of Costs and Revenues
The Agency performed its analysis separately for two groups of
mines: the coal mining sector as a whole, and the metal and nonmetal
mining sector as a whole. Based on a review of available sources of
public data on the mining industry, the Agency believes that a
quantitative analysis of the impacts on various mining subsectors (that
is, beyond the 4-digit SIC level) is not feasible. The Agency requested
comments, however, on whether there are special circumstances that
warrant separate quantification of the impact of this final rule on any
mining subsector and information on how it might readily obtain the
data necessary to conduct such a quantitative analysis. The Agency is
fully cognizant of the diversity of mining operations in each sector,
and has applied that knowledge as it developed the final rule.
In determining revenues for coal mines, MSHA multiplied coal
production data (in tons) for mines in specific size categories
(reported to MSHA quarterly) by $18.14 per ton, Department of Energy
(1997). For metal and nonmetal mines, the Agency estimated revenues for
specific mine size categories as the proportionate share of these
mines' contribution to the Gross National Product, Department of
Interior (1998).
Results of Screening Analysis
As shown in the following chart, for coal mine operators with fewer
than 20 employees, the estimated yearly cost of the final rule is $400
per mine operator, and estimated yearly costs as a percentage of
revenues are 0.08 percent. As shown in the next chart, for coal mine
operators with 500 or fewer employees, the estimated yearly savings
from the final rule are $634 per mine operator. The savings are due to
the elimination of existing coal industry requirements for performing
and recording semiannual surveys and other related surveys and reports.
Table 1.--The Impact of Final Rule on the Coal Mining Industry *
----------------------------------------------------------------------------------------------------------------
Estimated Cost as
Mine type Estimated Estimated revenue cost per percent of
costs mine revenue
----------------------------------------------------------------------------------------------------------------
Small (<20)........................................... $603,941="" $767,307,869="" $400="" 0.08="" large="">20)................................. 763,112 18,964,691,818 727 0.00
----------------------------------------------------------------------------------------------------------------
* Source: Preliminary Data 1997 from CM441 and Department of Energy/Energy Information Agency. Annual Energy
Review 1997. POE/EIA-038497. July 1998. P. 187.
Table 2.--The Impact of Final Rule on the Coal Mining Industry *
----------------------------------------------------------------------------------------------------------------
Estimated Cost as
Mine type Estimated Estimated revenue cost per percent of
costs mine revenue
----------------------------------------------------------------------------------------------------------------
Small (500)................................ $1,296,461 $19,038,974,646 $508 0.01
Large (<500).......................................... 70,592="" 693,025,041="" 6,403="" 0.01="" ----------------------------------------------------------------------------------------------------------------="" *="" source:="" preliminary="" data="" 1997="" from="" cm441="" and="" department="" of="" energy/energy="" information="" agency.="" annual="" energy="" review="" 1997.="" poe/eia-038497.="" july="" 1998,="" p.="" 187.="" as="" shown="" in="" the="" following="" chart,="" for="" metal/nonmetal="" mines="" with="" fewer="" than="" 20="" employees,="" the="" estimated="" yearly="" cost="" of="" the="" final="" rule="" is="" $414="" per="" mine="" operator,="" and="" estimated="" costs="" as="" a="" percentage="" of="" revenues="" are="" 0.04="" percent.="" as="" shown="" in="" the="" next="" chart,="" for="" metal/nonmetal="" mine="" operators="" with="" 500="" or="" fewer="" employees,="" the="" estimated="" yearly="" cost="" is="" $617="" per="" mine="" operator,="" and="" estimated="" costs="" as="" a="" percentage="" of="" revenues="" are="" 0.02="" percent.="" [[page="" 49555]]="" table="" 3.--the="" impact="" of="" final="" rule="" on="" the="" metal/nonmetal="" mining="" industry="" *="" ----------------------------------------------------------------------------------------------------------------="" estimated="" cost="" as="" mine="" type="" mine="" costs="" estimated="" revenue="" cost="" per="" percent="" of="" mine="" revenue="" ----------------------------------------------------------------------------------------------------------------="" small=""><20)........................................ $4,321,282="" $10,651,022,009="" $460="" 0.04="" large="">20).............................. 3,056,036 27,348,977,991 1,945 0.01
----------------------------------------------------------------------------------------------------------------
* Source: Preliminary Data 1997 from CM441 and Department of Interior, Bureau of Mines, Mineral.
Table 4.--Distribution of Mine Operations and Employment by Mine Type and Size Including Independent Contractors
and Contractor Workers Potentially Affected by the Final Rule *
----------------------------------------------------------------------------------------------------------------
Coal Metal/nonmetal
-----------------------------------------------------------------------------
Mine Size (No. of employees) No. of No. of Miners per No. of No. of Miners per
mines miners mine mines miners mine
----------------------------------------------------------------------------------------------------------------
Small (<20)....................... 2,401="" 14,347="" 5.97="" 10,098="" 56,859="" 5.63="" large="">20)............. 1,133 82,142 72.48 1,666 122,378 73.45
-----------------------------------------------------------------------------
Total....................... 3,535 96,489 27.30 11,764 179,238 15.24
----------------------------------------------------------------------------------------------------------------
* Source: Table 2 and Table 3. Office workers are not included in these employment figures.
In all cases, the cost of complying with the final rule is less
than one percent of revenues, well below the level suggesting that the
final rule might have a significant impact on a substantial number of
small entities. Accordingly, MSHA has certified that there is no such
impact on small coal mines or small metal/nonmetal mines.
Regulatory Alternatives Considered
The limited impacts on small mines, regardless of size definition,
reflect decisions by MSHA not to include more costly regulatory
alternatives. In considering regulatory alternatives for small mines,
MSHA must observe the requirements of its authorizing statute. Section
101(a)(6)(A) of the Mine Act requires the Secretary to set standards
which most adequately assure, on the basis of the best available
evidence, that no miner will suffer material impairment of health over
his/her working lifetime. In addition, the Mine Act requires that the
Secretary, when promulgating mandatory standards pertaining to toxic
materials or harmful physical agents, consider other factors, such as
the latest scientific data in the field, the feasibility of the
standard, and experience gained under the Act and other health and
safety laws. Thus, the Mine Act requires that the Secretary, in
promulgating a standard, attain the highest degree of health and safety
protection for the miner, based on the ``best available evidence,''
with feasibility as a consideration.
As a result of this statutory requirement, MSHA considered two
alternatives that would have significantly increased costs for small
mine operators lowering the permissible exposure level to a
TWA8 of 85 dBA, and lowering the exchange rate to 3 dB. In
both cases, the scientific evidence in favor of these approaches was
strong, but commenters offered divergent views on the alternatives. In
both cases, for the purpose of this final rule, MSHA has concluded that
it would not be feasible for the mining industry to accomplish these
more protective approaches. The impact of these approaches on small
mine operators was an important consideration in this regard.
Further, MSHA proposed using an 80-dBA threshold for determining
the permissible exposure level. If the Agency had done this, the number
of mines with exposure levels at or above the permissible exposure
level would have increased substantially. Accordingly, with more mines
above this level, the total cost of compliance would have been higher,
including penalties. Many commenters opposed the change in the
threshold. They believed that the current 90-dBA threshold was
sufficient for achieving adequate health protection for miners and was
compatible with OSHA's noise standard. Additionally, as discussed in
more detail later in the preamble, MSHA did not intend to change the
permissible exposure level for noise. A change in the threshold would
have had this effect. For these reasons, the final rule includes the
existing threshold for the permissible exposure level.
Under the proposal, the mine operator would have had to make
certain that miners exposed above the permissible exposure level take
the audiometric examination. Several commenters expressed concerns
about the enforceability of this provision. MSHA considered these
concerns, and under the final rule, audiometric testing is voluntary.
In this regard, it is also compatible with OSHA's noise standard.
In addition, under the proposal, mine operators would not have been
allowed to use hearing protectors as a substitute for the 14-hour quiet
period prior to an audiogram. Mine operators had stated that they could
not, without substantial burden to production and management, meet this
requirement. Some noted that in cases in which the audiometric testing
cannot be scheduled on a day after a non-work day, the only way to
ensure a 14-hour quiet period was to pay the miner not to work. Under
the final rule, mine operators may use hearing protectors as a
substitute for the quiet period. Again, this is compatible with OSHA's
noise standard.
Paperwork Impact
In accordance with the Regulatory Flexibility Act and the Paperwork
Reduction Act of 1995, MSHA has analyzed the paperwork burden for both
metal and nonmetal and coal mines. While the final rule results in a
net paperwork burden decrease for large coal mines in year one and both
small and large coal mines after year one, there will be an increase in
paperwork burden hours for small coal mines in year one and in metal
and nonmetal mines' year one and every year thereafter.
For small coal mines with fewer than 20 miners the final rule will
result in an increase of about 485 paperwork burden hours in year one.
After year one there will be a savings of 4,438 paperwork burden hours
for small coal mines. For large coal mines with 20 or more miners, the
final rule will result in a decrease of about 10,405 paperwork
[[Page 49556]]
burden hours in year one, and a savings of 28,498 each year thereafter.
For metal and nonmetal mines, the final rule will result in an increase
of paperwork burden hours for both small and large mines. There will be
an increase of 33,955 paperwork burden hours for small metal and
nonmetal mines and increase of 38,183 paperwork burden hours for large
metal and nonmetal mines in year one. After year one, there will be an
increase of 15,526 paperwork burden hours per year for small metal and
nonmetal mines, and an increase of 14,331 per year for large.
Although the substantial increases in paperwork burden hours result
from Secs. 62.175 and 62.180 for coal mines, these will be offset by
the net savings of Secs. 62.110-62.130, which eliminate current
requirements for biannual noise surveys and other miscellaneous reports
and surveys in that sector. However, for metal and nonmetal mines there
will be an increase in paperwork burden hours associated with complying
with the final rule.
As required by the Paperwork Reduction Act of 1995, MSHA has
included in its paperwork burden estimates the time needed to perform
tasks associated with information collection. For example, the final
rule requires a mine operator to notify a miner if the miner's noise
exposure equals or exceeds the action level. In order to determine if
notification is necessary, the mine operator must perform a dose
determination. MSHA has included the time needed for dose determination
in its burden estimate, as required under PRA 95.
Small Business Regulatory Enforcement Fairness Act (SBREFA)
In accordance with the Small Business Regulatory Enforcement
Fairness Act (SBREFA) amendments to the Regulatory Flexibility Act,
MSHA carefully considered all of the proposed requirements, in addition
to alternatives to the proposal, to ensure that the final rule would
provide the least burdensome impact necessary to promote miner health.
MSHA believes that it has complied with the SBREFA amendments.
The preamble to the proposed rule included a full discussion of
MSHA's preliminary conclusions about regulatory alternatives. The
public was invited to suggest additional alternatives for compliance.
MSHA is taking several actions to minimize the compliance burden on
small mines. The effective date of the final rule will be a full year
after its publication, to provide adequate time for small mines to
achieve compliance and for MSHA to brief the mining community about the
rule's requirements. Also, as stated previously, MSHA will mail a copy
of the final rule to every mine operator, which benefits small mine
operators. The Agency has committed itself to issuance of a compliance
guide for all mines; MSHA believes that compliance workshops or other
approaches will be valuable and the Agency will hold such workshops if
requested.
For this rulemaking's Regulatory Flexibility Analysis, the Agency
is using its traditional definition of ``small mine'' as a mine with
fewer than 20 employees, in addition to the SBA's definition of
operations with fewer than 500 employees, as required by the Regulatory
Flexibility Act. For purposes of this final rule, MSHA has continued
its past practice of using ``under 20 miners'' as the appropriate point
of reference, in addition to SBA's definition. Reviewers will note that
the paperwork and cost discussions continue to refer to the impacts on
``small'' mines with fewer than 20 employees. The Agency has not
established a definition of ``small entity'' for purposes of the final
rule. Based on this analysis, MSHA concludes that whatever definition
of ``small entity'' is eventually selected, the final noise rule does
not have a significant economic impact on a substantial number of small
entities.
Executive Order 13045: Protection of Children From Environmental Health
Risks and Safety Risks
In accordance with Executive Order 13045, MSHA has evaluated the
environmental health and safety effects of the final rule on children.
The Agency has determined that the final rule will have no adverse
effects on children.
Environmental Assessment
The final noise rule has been reviewed in accordance with the
requirements of the National Environmental Policy Act (NEPA) of 1969
(42 U.S.C. 4321 et seq.), the regulations of the Council of
Environmental Quality (CEQ) (40 CFR part 1500) and the Department of
Labor's NEPA compliance procedures (29 CFR part 11). In the Federal
Register of May 26, 1998 (63 FR 28496), MSHA made a preliminary
determination that the proposed noise rule was of a type that does not
have a significant impact on the human environment. In response, one
comment was received by the Agency. The commenter expressed a concern
that the Agency had not prepared an environmental assessment in
accordance with NEPA, the CEQ and the Department's procedural
regulations. MSHA's preliminary determination was based on its
Regulatory Impact Analysis which explained the costs and benefits of
the proposed rule. MSHA has complied with the requirements of the NEPA,
including the Department of Labor's compliance procedures and the
regulations of the Council on Environmental Quality. The Agency has not
received any new information or comments that would affect its previous
determination. As a result of the Agency's review of the final noise
rule, MSHA has concluded that the rule will not have significant
environmental impacts, and therefore neither an environmental
assessment nor an environmental impact statement is required. In
addition, MSHA believes that the final rule will indirectly aid the
environment since many of the engineering controls which control noise,
such as mufflers and curtains, also aid in controlling environmental
pollutants.
Executive Order 13084 (Consultation and Coordination With Indian Tribal
Governments)
MSHA certifies that the final rule does not impose substantial
direct compliance costs on Indian tribal governments. Further, MSHA
provided the public, including Indian tribal governments which operated
mines, the opportunity to comment on the proposal and to participate in
the public hearing process. No Indian tribal government applied for a
waiver or commented on the proposal.
Executive Order 12612 Federalism
Executive Order 12612, regarding federalism, requires that
agencies, to the extent possible, refrain from limiting state policy
options, consult with states prior to taking any actions which would
restrict state policy options, and take such actions only when there is
clear constitutional authority and the presence of a problem of
national scope. Because this final rule does not limit state policy
options, it complies with the principles of federalism and with
Executive Order 12612.
Unfunded Mandates Reform Act of 1995
MSHA has determined that, for purposes of Sec. 202 of the Unfunded
Mandates Reform Act of 1995, this final rule does not include any
Federal mandate that may result in increased expenditures by State,
local, or tribal governments in the aggregate of more than $100
million, or increased expenditures by the private sector of
[[Page 49557]]
more than $100 million. Moreover, the Agency has determined that for
purposes of Sec. 203 of that Act, this final rule does not
significantly or uniquely affect small governments.
Background
The Unfunded Mandates Reform Act was enacted in 1995. While much of
the Act is designed to assist the Congress in determining whether its
actions will impose costly new mandates on State, local, and tribal
governments, the Act also includes requirements to assist Federal
agencies to make this same determination with respect to regulatory
actions.
Analysis
Based on the analysis in the Agency's final Regulatory Economic
Analysis, the annualized cost of this final rule is approximately $8.9
million. Accordingly, there is no need for further analysis under
Sec. 202 of the Unfunded Mandates Reform Act.
MSHA has concluded that small governmental entities are not
significantly or uniquely impacted by the final regulation. The final
rule will impact approximately 15,299 coal and metal and nonmetal
mining operations; however, increased costs will be incurred only by
those operations (approximately 10,476 mines) where noise exposures
exceed the allowable limits. MSHA estimates that approximately 187 sand
and gravel or crushed stone operations are run by state, local, or
tribal governments and will be impacted by this rule.
When MSHA issued the proposed rule, the Agency affirmatively sought
input of any state, local, and tribal government which may be affected
by the noise rulemaking. This included state and local governmental
entities who operate sand and gravel mines in the construction and
repair of highways and roads. MSHA mailed a copy of the proposed rule
to these entities. No state, local or tribal government entity
commented on the proposed rule. When the final rule is published, MSHA
will mail a copy to all 187 entities.
IV. Miscellaneous
Permissible Exposure Level
The final rule affirms MSHA's initial determination, set out in the
proposal, that there is a significant risk for miners of material
impairment from noise exposures at or above an 8-hour time-weighted
average of 85 dBA. However, the final rule also comports with MSHA's
initial conclusion that it would not be either technologically or
economically feasible at this time for the mining industry to implement
a reduced permissible exposure level for noise, including a reduction
in the exchange rate. For these reasons the final rule does not reduce
the permissible exposure level, but it does require mine operators to
take a number of other actions that will substantially reduce miners'
risk of occupational noise-induced hearing loss.
MSHA will continue to examine closely the feasibility of a
reduction in the permissible exposure level for miners' noise exposure.
This will include, but is not limited to, assessment of the
availability and suitability of equipment retrofits for noise control,
evaluation of the state of existing noise control technology
appropriate for mining applications, and the availability of
alternative, and less noisy, equipment for various mining tasks. MSHA
intends to work closely with all segments of the mining community in
its continuing assessment of feasibility.
NIOSH Criteria Document
In March 1996, the National Institute for Occupational Safety and
Health (NIOSH) released for peer review a draft Criteria Document for
Occupational Noise Exposure, which was intended to update an earlier
NIOSH Criteria Document for Noise that had been issued in 1972. MSHA
summarized the recommendations of the draft Criteria Document in the
preamble to the proposed rule (61 FR 66369-66370), and considered the
draft Criteria Document recommendations, as well as comments that
addressed the draft Criteria Document, in developing this final rule.
In June 1998 NIOSH issued the final Criteria Document for
Occupational Noise Exposure, which in large part adopts the
recommendations of the 1996 draft Criteria Document, which, as
mentioned above, were considered as part of this rulemaking. However,
the final Criteria Document does include several recommendations which
differ from recommendations in the 1996 draft Criteria Document. The
main differences between the draft and the final Criteria Documents are
as follows:
1. Action level. In the draft document, NIOSH proposed what was
essentially an ``action level'' that would trigger establishment of
a Hearing Loss Prevention Program. The ``action level'' would have
been an 8-hour TWA of 85 dBA. The final Criteria Document does not
adopt the ``action level'' concept, and instead would trigger
establishment of a Hearing Loss Prevention Program at the
recommended exposure limit of an 85 dBA TWA8. Under
MSHA's final rule, a miner's noise exposure at 85 dBA
TWA8 requires enrollment of the miner in a Hearing
Conservation Program.
2. Ceiling Level. The NIOSH draft Criteria Document recommended
a ceiling at a 115 dBA sound pressure level. The final Criteria
Document recommends a 140 dBA sound pressure level ceiling limit for
continuous, varying, intermittent, or impulsive noise.
3. Dual Hearing Protection Level. The draft Criteria Document
did not make a recommendation for such a level. However, the final
Criteria Document recommends the use of dual hearing protection at
exposures exceeding a TWA8 of 100 dBA.
4. Quiet Period. The draft Criteria Document recommended a 14-
hour quiet period prior to a baseline audiogram, and would not
permit the use of hearing protectors as a substitute. The final
Criteria Document recommends a quiet period of 12 hours, and still
would not permit the use of hearing protectors in lieu of the quiet
period.
Rule Format
In the preamble to the proposed rule MSHA solicited comments on the
appropriate format for the final rule, providing examples for
commenters of alternate approaches. There was no clear consensus among
commenters to the proposal that the traditional format of MSHA's
regulations should be changed. As a result, the final rule adopts the
format of existing MSHA regulations.
Unlike the proposal the final rule does not include a question and
answer section. Instead, after publication of the final rule, MSHA will
develop and issue a compliance guide for the mining community to
facilitate its understanding of and compliance with the requirements of
the final rule. Additionally, MSHA is receptive to submission by the
mining community of suggestions for issues that should be addressed in
the compliance guide.
V. Material Impairment
Section 101(a)(6) of the Federal Mine Safety and Health Act of 1977
(Mine Act) provides that, in dealing with toxic materials or harmful
physical agents, standards set by the Secretary shall:
* * * most adequately assure on the basis of the best available
evidence that no miner will suffer material impairment of health or
functional capacity even if such miner has regular exposure to the
hazards dealt with by such standard for the period of his working
life.
MSHA has determined that there is a significant risk of material
impairment of health and functional capacity to miners from exposure to
workplace noise despite the existing noise standards, and the Agency's
rulemaking evidence supports this. MSHA anticipates that the final rule
will reduce, by approximately two-thirds, the number of miners who will
suffer a material impairment due to exposure to
[[Page 49558]]
occupational noise under the existing regulations.
MSHA's conclusion that there is a significant risk of material
impairment of health for workers exposed over their working lifetimes
to sound levels of 85 dBA is based on the Agency's definition of
material impairment, which is referred to in this preamble as the OSHA/
NIOSH-72 definition. Under the OSHA/NIOSH-72 definition, the excess
risk of a hearing impairment from occupational noise exposure is 15% or
one-hundred fifty-in-a-thousand miners at an 85 dBA TWA8
exposure for a working lifetime. The Supreme Court has indicated, in
discussing significant risk in the context of litigation under section
6(f) of the OSH Act, that OSHA is free to use conservative assumptions
in interpreting data so long as they are supported by reputable
scientific concepts, and that a one-in-a-thousand risk is significant.
Industrial Union Department, AFL-CIO v. American Petroleum Institute,
448 U.S. 607, 655 (1980) (the Benzene Case). If the Mine Act were to
impose the same risk-finding requirement as the OSH Act, MSHA's
determination of a significant risk of material impairment of health
falls well within the Supreme Court's direction to OSHA in the Benzene
Case.
Exposure to hazardous sound levels results in noise-induced hearing
loss. Noise-induced hearing loss is often described in terms of the
relationship between the sound level to which a person is exposed and
the duration of the exposure. Exposures to noise at sound levels equal
to or greater than the 8-hour average sound level of 85 dBA have been
shown to lead to hearing loss, which can be temporary or permanent.
Noise-induced hearing loss causes difficulty in hearing and
understanding speech. People suffering from significant noise-induced
hearing loss require even nearby persons to speak loudly and clearly to
be understood, and they are often frustrated by missing vital
information. Also, background noise affects the person's ability to
distinguish meaningful sounds from ambient noise. Little benefit can be
derived from the use of a hearing aid because it amplifies sound
indiscriminately, without increasing clarity, decreasing distortion, or
screening out unwanted sounds. Noise also produces secondary, non-
auditory effects.
Although the secondary effects of noise-induced hearing loss are
more difficult to identify, document, and quantify than the hearing
loss itself, recent laboratory and field studies have found an
association between noise and cardiovascular problems and other
illnesses such as hypertension. Studies also suggest that holding
exposure below a time-weighted average of 85 dBA will significantly
improve both psychological and physiological stress reactions.
Safety risks at the workplace may arise as a result of noise-
induced hearing loss. Workers suffering from noise-induced hearing loss
may not hear safety signals because of reduced hearing sensitivity to
higher frequencies. In addition, noise-induced hearing loss results in
the loss of the ability to distinguish between many pairs of
consonants, which makes speech incomprehensible. As a result, miners
suffering from noise-induced hearing loss may have trouble
understanding directions or warnings given by their supervisors or co-
workers.
Definition of Material Impairment
MSHA has determined that a 25 dB hearing level averaged over 1000,
2000, and 3000 Hz in both ears is the most appropriate gauge of a
miner's risk of developing significant noise-induced hearing loss. MSHA
therefore considers such a loss to constitute a material impairment in
hearing. MSHA's definition of material impairment is based on one
developed in 1972 by NIOSH and subsequently adopted by OSHA in its
noise standard for general industry, referred to below as the OSHA/
NIOSH-72 definition. (As noted by a commenter, the preamble to the
proposed rule incorrectly stated that the OSHA/NIOSH-72 definition
included the phrase ``in either ear.'' This mistake is corrected here
and in the final rule.) In addition, as discussed elsewhere in this
preamble, MSHA notes that it has not adopted the revised definition of
material impairment set forth in the final NIOSH Criteria Document
issued in June 1998. Throughout this preamble, therefore, MSHA will
continue to refer to the definition of material impairment developed by
NIOSH in 1972.
In nearly all studies of risk, material impairment from exposure to
noise is defined as a 25-dB hearing level. Hearing level is the
deviation in hearing sensitivity from audiometric zero. Positive values
indicate poorer hearing sensitivity than audiometric zero, while
negative values indicate better hearing. Audiometric zero is the lowest
sound pressure level that the average, young adult with normal hearing
can hear. Because of the widespread use of this definition in the
scientific community, MSHA has used it in the final rule.
Most definitions of hearing impairment are based solely on pure
tone audiometry, in which an audiometer is used to measure an
individual's threshold hearing level the lowest level of discrete
frequency tones that he or she can hear. The test procedures for pure
tone audiometry are relatively simple, widely used, and standardized.
Although there is little debate in the scientific community about the
usefulness of pure tone audiometry in assessing hearing loss, there is
some disagreement about the range of audiometric frequencies that
should be used in determining hearing loss.
When OSHA initially published its noise standard establishing noise
exposure limits for employees, most medical professionals used the 1959
criteria developed by the American Academy of Ophthalmology and
Otolaryngology (AAOO), a subgroup of the American Medical Association
(AMA). This definition (AAOO 1959) of hearing impairment is a hearing
level exceeding 25 dB, referenced to audiometric zero, averaged over
500, 1000, and 2000 Hz in either ear. The American Academy of
Otolaryngology Committee on Hearing and Equilibrium and the American
Council of Otolaryngology Committee on the Medical Aspects of Noise
(AAO-HNS) modified the 1959 criteria in 1979 by adding the hearing
level at 3000 Hz to the 500, 1000, and 2000 Hz frequencies. The AAOO
1959 and AAO-HNS 1979 definitions cover all types of hearing loss and
were designed for hearing speech under relatively quiet conditions. The
NIOSH-72 definition includes the higher frequencies, which are crucial
to the comprehension of speech under everyday conditions.
In its draft 1996 Criteria Document for occupational noise
exposure, NIOSH indicated that it was considering a new definition for
material impairment of a 25 dB or greater hearing loss at 1000, 2000,
3000, and 4000 Hz in both ears. This definition was a recommendation of
a Task Force to the American Speech-Language-Hearing Association (ASHA)
in 1981. In 1997, NIOSH conducted a reanalysis of the NIOSH-
Occupational Noise and Hearing Survey data and reevaluated the excess
risk of material hearing impairment incorporating the 4000 hertz
audiometric frequency in the definition of material impairment. (Excess
risk is defined by NIOSH as the percentage with material impairment of
hearing in an occupational noise exposed population after subtracting
the percentage who would normally incur such impairment from other
causes in a population not exposed to occupational noise.) In 1998,
NIOSH published the results of this reanalysis in its final Criteria
Document. The excess risk of developing occupational noise induced
[[Page 49559]]
hearing loss under the reassessment is 8%. The excess risk of
developing occupational noise induced hearing loss under the 1972 NIOSH
definition of material impairment is 15% for average noise exposure
level of 85 dBA. The final Criteria Document recommends that the
reanalysis reaffirms support for the 85 dBA NIOSH recommended exposure
limit.
The final rule does not adopt the revised NIOSH definition for
hearing impairment. Several commenters noted that this definition has
not been adopted by the scientific community, and no state workers'
compensation agency awards compensation for hearing impairment based
upon the current NIOSH hearing impairment criterion. Despite the fact
that noise-induced hearing loss usually first becomes detectable at
4000 Hz, MSHA finds that the scientific evidence does not, as yet,
support including 4000 Hz in the frequencies used for calculating
hearing impairment. Inclusion of test frequencies above 2000 Hz,
however, is necessary to show the effect of noise below 90 dBA on
hearing, so MSHA continues to include the 3000 Hz frequency. Several
commenters suggested that MSHA use the AAO-HNS 1979 definition of
material impairment. There were relatively few commenters in favor of
using the AAO-HNS 1979 definition. MSHA has excluded the 500 Hz
frequency from the definition of hearing impairment because it is not
as critical for understanding speech and is least affected by noise.
MSHA chose the hearing levels at 1000, 2000, and 3000 Hz on which to
base its definition of material impairment because high frequency
hearing is critically important to the understanding of speech, which
often takes place in noisy conditions. The Agency's determination is
consistent with OSHA's reasoning for its noise standard, and many
comments and studies cited support this approach.
Risk of Impairment
The risk of developing a material impairment becomes significant
over a working lifetime when workplace exposure to noise exceeds sound
levels of 85 dBA. Data reviewed by the Agency indicate that lowering
exposure from 90 dBA to 85 dBA does not eliminate the risk, it reduces
the risk by approximately half.
Typically, noise-induced hearing loss occurs first at 4000 Hz and
then progresses into the lower and higher frequencies. MSHA notes that
because noise does not affect hearing sensitivity equally across all
frequencies, the population defined as impaired will differ according
to the frequencies that are used in the measurement criteria. For
example, AAOO 1959 is weighted toward the lower frequencies, because it
was developed to determine an individual's ability to communicate under
quiet conditions. AAO-HNS, which includes 3000 Hz, is weighted toward
the higher frequencies. Because OSHA/NIOSH-72 is weighted even more
towards the higher frequencies due to the elimination of the hearing
level at 500 Hz, the population of those impaired due to noise exposure
will be greater than under the AAOO 1959 and AAO-HNS 1979 definition.
MSHA has found that there is no reliable mathematical relationship
among the three ways of assessing hearing impairment, so that direct
comparisons of their results are not possible. That is, it is not
possible to accurately predict the values computed using one definition
from values computed using either of the other two methods. In
addition, most of the raw data that would allow conversion from one
definition to another are no longer available. Nonetheless, the results
from all three approaches tend to demonstrate the same result.
Measuring Risk
MSHA could not determine an individual miner's risk from exposure
to particular levels of noise because at any given noise exposure, some
miners will suffer harm long before others, and a miner's
susceptibility cannot be measured in advance of exposure. However, as
MSHA noted in the proposal, risks can be determined for entire
populations. The probability of acquiring a material impairment of
hearing in a given population can be determined by extrapolating from
data obtained from a test population exposed to the same sound levels.
Three methods are generally used to express this population risk:
(1) The hearing level of the exposed population;
(2) The percentage of an exposed population meeting the selected
criteria; and
(3) The percentage of an exposed population meeting the selected
criteria minus the percentage of a non-noise exposed population meeting
the same criteria, provided both populations are similar, apart from
their occupational noise exposures.
MSHA has determined that the third method, commonly known as
``excess risk,'' provides the most accurate picture of the risk of
hearing loss resulting from occupational noise exposure. OSHA also used
this method in quantifying the degree of risk in the preamble to its
noise standard (46 FR 9739, 1983). This method allows the
differentiation of the population expected to develop a hearing
impairment due to occupational noise exposure from the population
expected to develop an impairment from non-occupational causes, such as
aging or medical problems.
Although studies of hearing loss in the rulemaking record
consistently indicate that exposure to increased sound levels or
increased duration results in increased hearing loss, the reported risk
estimates of occupational noise-induced hearing loss vary considerably
from one study to another. The variation is due to three factors:
(1) The definition of ``material impairment'' used (discussed
above);
(2) The screening of the control (non-noise-exposed) group; and
(3) The sound level below which material impairment from noise
exposure is not expected to occur.
In some of the data used by MSHA, researchers did not screen their
study and control populations, while in others they used a variety of
screening criteria. Theoretically, screening does not have a
significant impact on the magnitude of occupational noise-induced
hearing loss experienced by given populations as long as the same
criteria are used to screen both the noise-exposed and the non-noise-
exposed populations being compared. However, failure to take into
account any non-occupational noise exposure, loss of hearing
sensitivity due to aging, or both, can have a profound effect when
considering whether the subjects have exceeded an established
definition of material impairment. For example, if both the exposed and
control populations are screened to eliminate persons with a history of
military exposure, use of medicines harmful to the ear, noisy hobbies,
and conductive hearing loss from acoustic trauma or illness, the excess
risk would be significantly different from that determined using
unscreened populations.
The studies used by MSHA for the final as well as the proposed rule
generally assumed exposures below 80 dBA to be nonhazardous. Although a
few researchers--Kryter (1970) and Ambasankaran et al. (1981)--have
reported hearing loss from exposure to sound levels below 80 dBA, most
scientists believe that the risk of developing a material impairment of
hearing from exposure to such low levels over a working lifetime is
negligible. Accordingly, almost all noise risk studies consider the
population exposed only to average levels of noise below 80 dBA as a
``non-noise exposed''
[[Page 49560]]
control group. Thus, 80 dBA has become the lower sound level against
which other noise exposures are compared to determine the ``excess
risk.'' This position was adopted by OSHA in its evaluation of the risk
of hearing loss for its existing standard on hearing conservation.
Review of Study Data
As noted in the preamble to the proposed rule, Table 1 is derived
from the preamble to OSHA's noise standard (46 FR 4084). It displays
the percentage of the population expected to develop a hearing
impairment meeting the AAOO 1959 definition if exposed to the specified
sound levels over a working lifetime of 40 years. This is a compilation
of data developed by the U.S. Environmental Protection Agency (EPA) in
1973, the International Standards Organization (ISO) in 1975, and NIOSH
in 1972. EPA, ISO, and NIOSH developed their risk assessments based on
the AAOO 1959 definition, which was used by the original researchers.
Table 1.--OSHA Risk Table
----------------------------------------------------------------------------------------------------------------
Excess risk (%)
---------------------------------------------------
Sound level (dBA) NIOSH
ISO (1975) EPA (1973) (1972) Range
----------------------------------------------------------------------------------------------------------------
80.......................................................... 0 5 3 0-5
85.......................................................... 10 12 15 10-15
90.......................................................... 21 22 29 21-29
----------------------------------------------------------------------------------------------------------------
The excess risk of material impairment under the 1997/1998 NIOSH reanalysis is discussed earlier in this
preamble under Definition of Material Impairment.
Table 1 shows that the excess risk of material impairment after a
working lifetime at a noise exposure of 80 dBA is low. On the other
hand, a noise exposure of 85 dBA indicates a risk ranging from 10% to
15%. At a noise exposure of 90 dBA, the risk ranges from 21% to 29%.
Table 2 presents additional information on the risk assessments
calculated by NIOSH (Table XVII, Criteria Document, 1972), one portion
of which was included in Table 1. Table 2 is based on both the AAOO
1959 and the OSHA/NIOSH-72 definitions. It shows that NIOSH's risk
assessment found little difference between using the OSHA/NIOSH-72
definition and using the AAOO 1959 criteria.
Table 2.--NIOSH Risk Table
------------------------------------------------------------------------
Excess risk (%)
-------------------------
Sound level (dBA) OSHA/NIOSH-
72 AAOO 1959
------------------------------------------------------------------------
80............................................ 3 3
85............................................ 16 15
90............................................ 29 29
------------------------------------------------------------------------
Regarding how adjustments to the definitions used would affect the
excess risk figures above, MSHA agrees with several researchers
referred to by commenters. Suter (1988) estimates that the excess risk
would be somewhat higher if 500 Hz were excluded and 3000 Hz were
included in the definition of material impairment. Sataloff (1984)
reports that the effect of including hearing loss at 3000 Hz in the
AAOO 1959 definition of hearing impairment would dramatically increase
the prevalence of hearing impairment, as follows. After 20 years of
exposure to intermittent noise that peaked at 118 dBA, 3% of the
workers experienced hearing impairment according to the AAOO 1959
definition of hearing impairment. If the AAO-HNS 1979 definition is
used, the percentage increases to 9%. Royster et al. confirmed that the
exclusion of 500 Hz and the inclusion of 3000 Hz increased the number
of hearing impaired individuals in their study of potential workers'
compensation costs for hearing impairment (Royster et al., 1978). Using
an average hearing loss of 25 dB as the criterion, Royster found that
3.5% of the industrial workers developed a hearing impairment according
to AAOO 1959, 6.2% according to AAO-HNS 1979, and 8.6% according to the
OSHA/NIOSH-72 definition.
MSHA included the following three tables in the preamble to the
proposed rule in order to show data regarding the working lifetime risk
of material impairment based upon the three different definitions
commonly used for material impairment. Table 3 is based on AAO 1959,
Table 4 is based on AAO-HNS 1979, and, Table 5 is based on the OSHA/
NIOSH-72 definition. MSHA constructed these tables based on data
presented in Volume 1 of the Ohio State Research Foundation Report
(Melnick et al., 1980) commissioned by OSHA. The hearing level data
used to construct the tables are taken from summary graphs in that
report. The noise-exposed population was 65 years old, with 40 years of
noise exposure. Because the control group was not screened for the
cause of hearing loss, a high level of non-occupational hearing loss
may undervalue the excess risk from occupational noise exposure. The
researchers (Melnick et al., 1980) added the component of noise-induced
permanent threshold shift (the actual shift in hearing level due only
to noise exposure) to the control data.
MSHA did not receive any comments on the three tables reflecting
the predictable fact that, for any given population, the excess risk of
material impairment due to noise exposure will be greater using the
AAO-HNS 1979 definition than using the AAOO 1959 definition. Likewise,
the excess risk of material impairment due to noise exposure will be
greater using the OSHA/NIOSH-72 definition than using the AAO-HNS 1979
definition. All three tables show a smaller excess risk than did the
data presented in Table 1.
Table 3.--Risk of Impairment Using AAOO 1959 Definition of Impairment
and Using Melnick et al., 1980 Data
------------------------------------------------------------------------
Excess risk
Percent (percent)
Exposure with with noise
impairment exposure
------------------------------------------------------------------------
non-noise..................................... 26.8 0.0
80 dBA........................................ 26.8 0.0
85 dBA........................................ 27.8 1.0
90 dBA........................................ 31.4 4.6
------------------------------------------------------------------------
Table 4.--Risk of Impairment Using AAO-HNS 1979 Definition of Impairment
and Using Melnick et al., 1980 Data
------------------------------------------------------------------------
Excess risk
Percent (percent)
Exposure with with noise
impairment exposure
------------------------------------------------------------------------
non-noise..................................... 41.6 0.0
80 dBA........................................ 41.8 0.2
[[Page 49561]]
85 dBA........................................ 44.4 2.8
90 dBA........................................ 50.0 8.4
------------------------------------------------------------------------
Table 5.--Risk of Impairment Using OSHA/NIOSH-72 Definition of
Impairment and Using Melnick et al., 1980 Data
------------------------------------------------------------------------
Excess risk
Percent (percent)
Exposure with with noise
impairment exposure
------------------------------------------------------------------------
non-noise..................................... 48.5 0.0
80 dBA........................................ 48.7 0.2
85 dBA........................................ 51.5 3.0
90 dBA........................................ 57.9 9.4
------------------------------------------------------------------------
The excess risk in Table 1 represents the risk assessments
conducted by ISO, EPA, and NIOSH in three different years during the
early 1970's. All three agencies used the same definition of impairment
(AAOO 1959) in evaluating available studies. Their results are similar.
MSHA applied three different definitions of hearing impairment to
the same data (Melnick 1980) to show that the excess risk of impairment
varies depending on how you define impairment. Tables 3, 4, and 5
present the results of this analysis. Because Melnick did not screen
his control group for the cause of the hearing loss (could be non-
occupational noise exposure), the amount of hearing loss in the
supposed non-noise exposed group is high. By subtracting the value for
the non-noise exposed (control) group from the values determined for
groups with different levels of occupational noise exposure, we
determined the excess risk for populations exposed at that level.
Tables 6 and 7 were also included in the preamble to the proposed
rule to show data derived by Melnick in Forensic Audiology (1982) for
risk of impairment due to noise exposure. These tables show the results
of applying the AAO-HNS 1979 method to a population that is 60 years
old with 40 years of exposure to the specified sound levels. In both
tables, the data represent the noise-induced permanent threshold shift
calculated by Johnson, but the screening criteria used in the two
tables are different. Melnick's data in Table 6 are based upon the
screened age-induced hearing loss data (that is, they are screened for
non-occupational hearing loss) of Robinson and Passchier-Vermeer,
whereas Table 7 is based on unscreened, non-occupational hearing loss
data from the 1960-62 U.S. Public Health Survey.
Overall, the excess risk information presented in these tables is
closer to that in Table 1 than to that in Tables 3, 4, and 5, but still
differs. Tables 6 and 7 directly illustrate the effect of screening
populations in determining excess risk due to occupational noise
exposure. Comparison of these tables shows that the percentage of
workers with hearing impairment is greater in the table constructed
with an unscreened population as the base.
Table 6.--Risk of Impairment Using Age-induced Hearing Loss Data of
Passchier-Vermeer and Robinson
------------------------------------------------------------------------
Excess risk
Percent (percent)
Exposure with with noise
impairment exposure
------------------------------------------------------------------------
75 dBA........................................ 3 0
80 dBA........................................ 5 2
85 dBA........................................ 9 6
90 dBA........................................ 21 18
------------------------------------------------------------------------
Table 7.--Risk of Impairment Using Non-occupational Hearing
------------------------------------------------------------------------
Excess risk
Percent (percent)
Exposure with with noise
impairment exposure
------------------------------------------------------------------------
75 dBA........................................ 27 0
80 dBA........................................ 29 2
85 dBA........................................ 33 6
90 dBA........................................ 40 13
------------------------------------------------------------------------
Chart 1 incorporates the risk assessment results of Tables 3, 4, 5,
6, and 7.
[[Page 49562]]
[GRAPHIC] [TIFF OMITTED] TR13SE99.000
Note that the data from both Table 6 and Table 7 used the AAO-HNS 1979
definition. The exact numbers of those at risk varies with the study
because of the definition of material impairment used, the screening
criteria used, and the selection of the control group. Despite these
differences, the data consistently demonstrate three points:
(1) The excess risk increases as noise exposure increases;
(2) There is a significant risk of material impairment of hearing
loss for workers exposed over their working lifetimes to sound levels
of 85 dBA; and
(3) Lowering the exposure from 90 dBA to 85 dBA reduces the excess
risk of developing a material impairment by approximately half.
Related Studies of Worker Hearing Loss
The preamble to the proposed rule indicated that MSHA examined a
large body of data on the effects of varying industrial sound levels on
worker hearing sensitivity, including studies that specifically
addressed the mining industry. Regardless of the industry in which the
data were collected, MSHA found that exposures to similar sound levels
results in similar degrees of material impairment in workers. These
studies support the conclusions reached in the previous section about
the risk of impairment at different sound levels.
NIOSH (Lempert and Henderson, 1973) published a report in which the
relationship of noise exposure to noise-induced hearing loss was
described. NIOSH studied 792 industrial workers whose daily noise
exposures were 85 dBA, 90 dBA, and 95 dBA. The noise-exposed workers
were compared to a control group whose noise exposures were lower than
80 dBA. The exposures were primarily to steady-state noise, but the
exposure levels fluctuated slightly in each category. Both groups were
screened to exclude non-occupational noise exposure or medical
complications. The subjects ranged in age from 17 to 65 years old. The
report clearly shows that workers whose noise exposures were 85 dBA
experienced more hearing loss than the control group. In addition, as
the noise exposures increased to 90 dBA and 95 dBA, the magnitude of
the hearing loss increased.
NIOSH reanalyzed these data in a report, ``Reexamination of NIOSH
Risk Estimates'' (Prince et al., 1997), which was published after
MSHA's proposed rule. The authors reanalyzed the data from NIOSH's
report (Lempert and Henderson, 1973) that had established a dose-
response relationship for noise. In the original study, Lempert and
Henderson had interpreted response to be proportional to dose. Prince
interpreted the relationship to be a more complex one, and this
analysis resulted in a better fit with the data. Prince's approach also
consistently yielded a slightly lower excess risk. Thus, Prince
concluded that there is an excess risk of developing a hearing
impairment from a noise exposure of 85 dBA and above.
NIOSH (1976) published the results from a study on the effects of
prolonged exposure to noise on the hearing sensitivity of 1,349 coal
miners. From this study, NIOSH concluded that coal miners were losing
their hearing sensitivity at a faster rate than would be expected from
the measured environmental sound levels. While the majority of noise
exposures were less than a TWA8 of 90 dBA (only 12% of the
noise exposures exceeded a TWA8 of 90 dBA), the measured
hearing loss of the older coal miners was indicative of noise exposures
between a TWA8 of 90 dBA and 95 dBA. NIOSH offered as a
possible explanation that some miners are exposed to ``very intense
noise'' for a sufficient number of months to cause the hearing loss.
Coal miners in the NIOSH (1976) study experienced a higher
incidence of hearing impairment than the non-occupational-noise-exposed
group (control group) at each age. Using the OSHA/NIOSH-72 definition
of material impairment, 70% of 60-year-old coal miners were impaired
while only a third of the control group were. This would correspond to
an excess risk of 37%.
NIOSH also sponsored a study, conducted by Hopkinson (1981), on the
[[Page 49563]]
prevalence of middle ear disorders in coal miners. In this study, the
hearing sensitivity of 350 underground coal miners was measured. The
results of this study supported the results of the 1976 NIOSH study on
the hearing sensitivity of underground coal miners (i.e., coal miners
had worse hearing than the controls); the measured median hearing
levels of the miners were the same in the two studies.
OSHA's 1981 preamble to its Hearing Conservation Amendment referred
to studies conducted by Baughn; Burns and Robinson; Martin et al.; and
Berger et al. Baughn (1973) studied the effects of average noise
exposures of 78 dBA, 86 dBA, and 90 dBA on 6,835 industrial workers
employed in midwestern plants producing automobile parts. Noise
exposures for these workers were measured for 14 years and, through
interviews, exposure histories were estimated as far back as 40 years.
Neither the control group nor the noise-exposed groups were screened
for anatomical abnormalities of the ear.
Baughn used this data to estimate the hearing levels of workers
exposed to 80 dBA, 85 dBA, and 92 dBA and extrapolated the exposures up
to 115 dBA. Based upon the analysis, 43% of 58-year-old workers exposed
for 40 years to noise at 85 dBA would meet the AAOO 1959 definition for
hearing impairment. Thirty-three percent of an identical but non-noise
exposed population would be expected to meet the same definition of
impairment. The excess risk from exposure to noise at 85 dBA would
therefore be 10%. Using the same procedure, the excess risk for 80 dBA
is 0% and for 90 dBA is 19%.
Burns and Robinson (1970) studied the effects of noise on 759
British factory workers exposed to average sound levels between 75 dB
and 120 dB with durations ranging between one month and 50 years. The
control group consisted of 97 non-noise exposed workers. Thorough
screening removed workers with unknown exposure histories. Also
excluded were people with ear disease or abnormalities and language
difficulty. Burns and Robinson analyzed 4,000 audiograms and found that
the hearing levels of workers exposed to low sound levels for long
periods of time were equivalent to those of other workers exposed to
higher sound levels for shorter durations. From the data, the
researchers developed a mathematical model that predicts hearing loss
between 500 Hz and 6000 Hz in certain segments of the exposed
population.
Using the Burns and Robinson mathematical model, MSHA constructed
Chart 2. The chart shows that a noise exposure of 85 dBA over a 40-year
career is clearly hazardous to the hearing sensitivity of 60-year-old
workers. Chart 2 compares the same three definitions of impairment to
the Burns-Robinson Model as used in Tables 3, 4, and 5 with the Melnick
data. Chart 2 confirms the relationship between the definition of
impairment and the computation of excess risk.
[GRAPHIC] [TIFF OMITTED] TR13SE99.001
The prevalence of hearing loss in a group of 228 Canadian steel
workers, ranging in age from 18 to 65 years of age, was compared to a
control group of 143 office workers in a study conducted by Martin et
al. (1975). The researchers reported that the risk of hearing
impairment (average of 25 dB at 500, 1000, and 2000 Hz) increases
significantly between 85 dBA and 90 dBA. Up to 22% of these workers
would be at risk of incurring a hearing impairment with a
TWA8 90 dBA permissible exposure level compared to 4% with a
TWA8 85 dBA permissible exposure level. Both the noise-
exposed and the control groups were screened to exclude workers with
non-occupational hearing loss.
Passchier-Vermeer (1974) reviewed the results of eight field
investigations on hearing loss among 20 groups of workers. About 4,600
people were included in the analysis. The researcher concluded that the
limit of permissible noise exposure (defined as the maximum level which
did not cause measurable noise-induced hearing loss, regardless of
years of exposure) was shown to be 80 dBA. Furthermore, the researcher
found that noise exposures
[[Page 49564]]
above 90 dBA caused considerable hearing loss in a large percentage of
employees and recommended that noise control measures be instituted at
this level. The researcher also recommended that audiometric testing be
implemented when the noise exposure exceeds 80 dBA.
Berger, Royster, and Thomas (1978) studied 42 male and 58 female
workers employed at an industrial facility and a control group of 222
persons who were not exposed to occupational noise. Of the 322
individuals included in the study, no one was screened for exposures to
non-occupational noise such as past military service, farming, hunting,
or shop work, since these exposures were common to all. The researchers
found that exposure to a daily steady-state Leq of 89 dBA
for 10 years caused a measurable hearing loss at 4000 Hz
(Leq is an average sound level computed on a 3-dB exchange
rate). According to the researchers, the measurable loss was in close
agreement with the predictions of Burns and Robinson, Baughn, NIOSH,
and Passchier-Vermeer.
Studies of Impact of Lower Sound Levels
Table 8 reproduces the most recent data on the harm that can occur
at lower sound levels, found in the International Standards
Organization's publication ISO 1999 (1990). The noise exposures for the
population ranged between 75 dBA and 100 dBA. Table 8 presents the mean
and various percentages of the hearing level of a 60-year-old male
exposed to noise for 40 years. The noise-induced permanent threshold
shift in hearing was combined with the age-induced hearing loss values
to determine the total hearing loss. The age-induced hearing loss
values were from an unscreened population representing the general
population.
Table 8.--Hearing Level Resulting From Selected Noise Exposures
----------------------------------------------------------------------------------------------------------------
Hearing level in dB
Sound level in dBA ---------------------------------------------------
500 Hz 1000 Hz 2000 Hz 3000 Hz
----------------------------------------------------------------------------------------------------------------
80.......................................................... 12 6 10 30
85.......................................................... 12 6 11 33
90.......................................................... 12 6 16 42
----------------------------------------------------------------------------------------------------------------
Information about the effects of lower noise exposures on hearing
are especially valuable in attempting to identify subpopulations
particularly sensitive to noise. The Committee on Hearing,
Bioacoustics, and Biomechanics of the National Research Council (CHABA)
(1993) reviewed the scientific literature on hazardous exposure to
noise. The report reaffirmed many of the earlier findings of the
Committee. Based on temporary threshold shift (TTS) studies, the report
suggests that to prevent noise-induced hearing loss, exposures must
remain below 76 dBA to 78 dBA. Based on field studies, the report
suggests that, to guard against any permanent hearing loss at 4000 Hz,
the sound level should be less than 85 dBA, and possibly less than 80
dBA. Finally, the report suggests that therapeutic drugs, such as
aminoglycoside antibiotics and salicylates (aspirin), can interact
synergistically with noise to yield more hearing loss than would be
expected by either stressor alone.
Few current studies of unprotected U.S. workers exposed to a
TWA8 between 85 and 90 dBA are available, because the
hearing conservation program of OSHA's noise standard requires
protection at those levels for most industries (the exception being
employers engaged in oil and gas well drilling and servicing
operations). The difficulty in constructing new retrospective studies
of U.S. workers has been noted by Kryter (1984) in his chapter entitled
``Noise-Induced Hearing Loss and Its Prediction.'' He states that due
to the global trend in the last decade to institute noise control and
hearing conservation programs, new retrospective studies are no longer
feasible. Kryter believes that the retrospective studies of Baughn,
Burns and Robinson, and the U.S. Public Health Service are thus the
best available on the subject of noise-induced permanent threshold
shift. Kryter developed a formula to derive the effective noise
exposure level for damage to hearing from the earlier studies and
determined the noise-induced permanent threshold shift at different
percentiles of sensitivity at various audiometric test frequencies for
a population of workers.
Studies of workers in other countries can provide valuable
information in assessing the consequences of workplace noise exposure
between 85 dBA and 90 dBA. Differences in socioeconomic factors such as
recreational noise exposure, use of medicines harmful to the ear, and
inflammation of the middle ear (otitis media) make it difficult to
directly apply the results of studies of workers from other countries.
However, MSHA has determined that these studies can be used as further
support for the existence of a risk in the 80 to 90 dBA range.
Rop, Raber, and Fischer (1979) studied the hearing loss of 35,212
male and female workers in several Austrian industries, including
mining and quarrying. The researchers measured the hearing levels of
workers exposed to sound levels ranging from less than 80 dBA up to 115
dBA and arranged them into eight study groups based on average
exposures. Assuming that exposure to sound levels less than 80 dBA did
not cause any hearing loss, they assigned workers exposed to these
levels to the control group. The researchers reported that workers with
6 to 15 years of exposure at 85 dBA had significantly worse hearing
than the control group. For the five groups whose exposure was between
80 dBA and 103.5 dBA, hearing loss tended to increase steadily during
their careers but leveled off after 15 years. In contrast, for workers
exposed to sound levels above 103.5 dBA, hearing loss continued to
increase beyond 15 years.
A statistical method for predicting hearing loss was developed
using the data collected in the Rop study. The researchers predicted
that 20.1% of the 55-year old males in the control group with 15 years
of work experience would incur hearing loss. For a comparable group of
males with exposures at 85 dBA the risk increased to 41.6%; at 92 dBA
the risk increased to 43.6%; and at 106.5 dBA the risk increased to
72.3%. The study concluded that exposure to sound levels at or above 85
dBA damaged workers' hearing.
A study (Schwetz et al., 1980) of 25,000 Austrian workers concluded
that the workers exposed to sound levels between 85 dBA and 88 dBA
experienced greater hearing loss than workers exposed to sound levels
less than 85 dBA. The study further
[[Page 49565]]
concluded that at 85 dBA there is no hearing recovery, ultimately
causing noise-induced hearing loss. Schwetz, therefore, recommended 85
dBA as the critical intensity--the permissible exposure limit.
Stekelenburg (1982) calculated age-induced hearing loss according
to Spoor and noise-induced hearing loss according to Passchier-Vermeer.
Based upon these calculations, Stekelenburg suggested 80 dBA as the
acceptable level for noise exposure over a 40 year work history. At
this exposure, Stekelenburg calculates that socially impaired hearing
due to noise exposure would be expected in 10% of the population.
A study of 537 textile workers by Bartsch et al. (1989), which
defined socially significant hearing loss as a 40 dB hearing level at
3000 Hz, found that the hearing loss resulting from exposures below 90
dBA mainly occurs at frequencies above 8000 Hz (these frequencies are
not normally tested during conventional audiometry). Even though the
study concluded that the hearing loss was not of ``social importance,''
it did support a reduced hearing loss risk criterion of 85 dBA be used
to protect the workers' hearing.
With the exception of the Bartsch study, the results of the foreign
studies are generally consistent with those of U.S. workers. The
Bartsch conclusion that the hearing loss is not of ``social
importance'' is not supported by the many studies, discussed earlier,
that point to the importance of good hearing sensitivity at 3000 Hz in
order to understanding speech in everyday, noisy environments. Based on
experience, MSHA has found that people will encounter hearing
difficulty before their hearing loss level reaches 40 dB at 3000 Hz.
One commenter stated that the studies cited by MSHA in justifying
the risk of material impairment at exposures below 90 dBA were based on
sound levels determined using older instrumentation. Assuming that MSHA
would be using more modern instrumentation for compliance purposes, he
suggested that the Agency should not use the old data and studies. The
commenter suggested that MSHA either raise or retain the criterion
level of a TWA8 of 90 dBA or have the studies re-done with
newer instrumentation before proceeding with rulemaking. MSHA maintains
that the studies remain valid, however, because they were conducted
using methodologies based on sound level meters. The studies, like the
final rule, were based on the standardized definitions of A-weighting
network and slow response and usually measured steady-state noise.
Therefore, the studies are reliable and applicable. MSHA's risk
assessment is based upon the best scientific data available to the
Agency, as required by the Mine Act.
Reported Hearing Loss Among Miners
To confirm the magnitude of the risks of noise-induced hearing loss
among miners, MSHA examined the following evidence of reported hearing
loss among miners.
Audiometric Databases
Audiometric testing is not currently required in metal and nonmetal
mining and is offered in coal mining only after a determination of
overexposure to noise. However, in connection with its ongoing
assessments of the effectiveness of the current standards in protecting
miner health, MSHA has obtained two audiometric databases consisting of
20,022 audiograms conducted on 3,439 coal miners and 42,917 audiograms
conducted on 9,050 metal and nonmetal miners. The audiometric
evaluations on the coal miners were conducted between 1971 and 1994,
mostly during the latter years. The audiograms on metal and nonmetal
miners were collected between 1974 and 1995. Each audiogram in the data
set contained a miner identification number, age, date of test, and
audiometric thresholds for each ear at 500, 1000, 2000, 3000, 4000, and
6000 Hz. Supplemental data such as dates of employment, noise
exposures, use of protective equipment, and training histories were not
provided. MSHA asked NIOSH to examine the audiometric data and both
MSHA and NIOSH (Franks, 1996) have performed analyses of the coal miner
database.
Coal Miner Audiometric Data
Franks used a computer expert system to screen the data for year-
to-year consistency of the audiograms, test-room background noise, and
asymmetry in hearing that might indicate a unilateral loss of hearing
(which is not characteristic of occupational noise-induced hearing
loss). More than 2,500 questionable audiograms were reviewed by NIOSH
audiologists.
The final screened database consisted of 17,260 audiograms
representing 2,871 coal miners. It was compared to the database in
Annex A of ``ISO-1999.2 Acoustics--Determination of Occupational Noise
Exposure and Estimation of Noise-Induced Hearing Loss.'' NIOSH's report
entitled ``Analysis of Audiograms for a Large Cohort of Noise-Exposed
Miners'' (NIOSH, 1996) indicates that 90% of these coal miners had a
hearing impairment (defined as an average 25-dB hearing level at 1000,
2000, 3000, and 4000 Hz) by age 51 compared with only 10% of the
general population. Even at age 69, only 50% of the non-noise-exposed
population acquire a hearing impairment.
By age 35 the average miner has a mild hearing loss, and 20% of
miners have a moderate loss. By age 64, fewer than 20% of the miners
have marginally normal hearing, while 80% have moderate to profound
hearing loss. In contrast, 80% of the non-noise-exposed population will
not acquire a hearing loss as severe as the average miner's, regardless
of how long they live. Further, Franks concluded that miners, after
working 20 to 30 years, could find themselves in life-threatening
situations resulting from their inability to hear safety signals and
roof talk.
Metal and Nonmetal Miner Audiometric Data
NIOSH used a computer expert system to screen the audiometric data
on metal and nonmetal miners. The data were screened for year-to-year
consistency of the audiograms, test room background noise, and
asymmetry in hearing that might indicate a loss of hearing in only one
ear (not characteristic of an occupational noise-induced hearing loss).
The expert system identified 20,429 questionable audiograms, and a
subset of 1000 were reviewed by an audiologist.
The final screened database consisted of 22,488 audiograms
representing 5,244 metal and nonmetal miners. The data were compared to
those in Annex A of ``ISO-1999.2 Acoustics--Determination of
Occupational Noise Exposure and Estimation of Noise-Induced Hearing
Loss.'' NIOSH's report, entitled ``Prevalence of Hearing Loss for
Noise-Exposed Metal/Nonmetal Miners'' (NIOSH, 1997), supports the
conclusions of earlier scientific studies that metal and nonmetal
miners are losing their hearing sensitivity faster than the general
population. It indicates that, ``At age 20, approximately 2% have
hearing impairment, rising to around 7% at age 30, 25% at age 40, 49%
at age 50, and 70% by age 60. By contrast, 9% of the non-occupationally
noise-exposed have hearing impairment at age 50.'' Franks noted a
difference in the increase of hearing loss between men and women. He
also noted that, due to the NIOSH definition of hearing impairment used
in the study (inclusion of 4,000 Hz.), there was a sufficient degree of
hearing impairment in the population to cause communications problems,
because miners would have difficulty in understanding some consonants
whose
[[Page 49566]]
frequency is between 3,000 and 4,000 Hz.
MSHA received comments on both NIOSH studies. One commenter
asserted that Franks used an incorrect screening process for the
audiograms as well as the incorrect control group (ANNEX A of ISO R-
1999) and alleged other deficiencies in the studies. This commenter
stated that he reanalyzed the data using minimal screening of
audiograms, and compared it to the ``correct'' control group (Annex C
of ANSI S3.44-1996, ``Acoustics--Determination of Occupational Noise
Exposure'') estimating that the hearing impairment of the miners was
caused by noise exposure. The commenter concluded that both the coal
and metal and nonmetal audiometric data suggest that typical
occupational noise exposures are on the order of lifetime time-weighted
exposures of about 89 dBA. This commenter thus suggests that there is
no need for MSHA to continue with rulemaking, as the current
regulations are adequate in protecting miners' hearing sensitivity.
Some commenters concurred with the re-analysis of the NIOSH studies
performed by this commenter. MSHA notes, however, that there was no
significant difference between the control groups, as the International
Standards Organization 1999.2 standard and the American National
Standards Institute S3.44 standard are virtually identical--the ANSI
document having been adapted from the ISO document.
However, MSHA also received a great deal of support for the NIOSH
studies, which showed that the use of the Annex A control group--highly
screened audiometric data was appropriate and the use of Annex B or C
in the reanalysis was inappropriate.
One commenter stated, ``The use of Annex B * * * is questionable
because these data were not screened to exclude persons with
occupational noise exposure.''
MSHA agrees with Dr. Franks in that Annex A was the most
appropriate database for the analysis conducted because it is the only
database in ISO 1999 for which year-to-year changes in hearing and
prevalence of hearing impairment could be calculated. MSHA also
received support from commenters for the NIOSH studies. Additionally,
MSHA conducted its own research and determined that miners are still
losing more of their hearing sensitivity than non-noise-exposed
workers. Annex A is a more stringent screening method than Annex C
which was used by Dr. Clark. Annex A was selected because it represents
a highly screened sample, free from ``undue noise exposure'' and ear
disease.
Several researchers who studied the health status of miners
provided testimony based on numerous research reports. Their conclusion
was that miners have incurred a greater loss of hearing sensitivity
than the general population has. MSHA believes that the NIOSH studies
are valid evidence that supports the rule.
MSHA conducted a separate analysis of the audiometric data for coal
miners, using the 25 dB hearing level at 1000, 2000, and 3000 Hz
definition of material impairment of hearing. In order to reflect
current trends, the percentage of current coal miners (whose latest
audiogram was taken between 1990 and 1994) with material impairment of
hearing was compared to NIOSH's study on coal miners published in 1976.
The results are shown in Chart 3, along with NIOSH's 1976 results for
both the noise-exposed miners and the non-noise-exposed controls.
The data points for Chart 3 represent the mean hearing loss of both
ears at 1000, 2000, and 3000 Hz relative to audiometric zero. The top
line represents the 1976 (pre-noise-regulation) group, the middle line
represents the 1990-1994 (noise-regulated) group, and the bottom line
represents the non-noise-exposed group. Although there has been some
progress under the existing regulations, miners are still losing more
of their hearing sensitivity than non-noise-exposed workers. This is
true even if the analysis is limited to miners under 40 years of age
(that is, those who have worked only under the current coal noise
regulations).
[GRAPHIC] [TIFF OMITTED] TR13SE99.002
MSHA also analyzed the audiometric data for the number of standard
threshold shifts and reportable hearing loss cases. In the preamble to
the proposal, MSHA defined a standard threshold shift as a change in
hearing threshold level, relative to the miner's original or
supplemental baseline audiogram, of an average of 10 dB or more at
2000, 3000, and 4000 Hz in either ear. The final rule adopts this
definition. The importance of a standard threshold shift is that it
reveals that a permanent loss in hearing sensitivity
[[Page 49567]]
has occurred. When the change from the baseline averages 25 dB or more
at the same frequencies, the hearing loss must be reported to MSHA.
``Standard threshold shift'' and ``reportable hearing loss'' are
discussed in greater detail below.
For the second analysis, the first audiogram of each miner was
assumed to be the baseline. The last audiogram of each miner was
compared to the baseline. Neither audiogram was corrected for age-
induced hearing loss. Also, because of the lack of supporting data, it
was not possible to exclude non-occupational standard threshold shifts,
resulting in a greater number of standard threshold shifts. The results
of the 3,102 coal miners audiograms analyzed are presented in Chart 4.
[GRAPHIC] [TIFF OMITTED] TR13SE99.003
Chart 4 clearly shows that many of the coal miners were found to
have a standard threshold shift. The likelihood of acquiring a standard
threshold shift generally increases with advancing age. The MSHA
analysis was conservative in that only the first and last audiograms
were included, resulting in each miner having only one standard
threshold shift. In fact, a miner may have experienced multiple
standard threshold shifts.
In addition to the above audiometric data, two NIOSH studies
mentioned in the section of this preamble on risk of impairment support
MSHA's conclusion that miners are at risk of noise-induced hearing
loss. In the 1976 NIOSH study, although the majority of noise exposures
were less than 90 dBA, approximately 70% of the 60-year old coal miners
had experienced a material impairment of hearing using the OSHA/NIOSH-
72 definition. The Hopkinson (1981) NIOSH study also supports the
earlier NIOSH results.
Data Provided by Commenters
Two commenters to the proposed rule provided information on the
hearing sensitivity of miners. The first commenter estimated that 45 to
50% of employed miners have experienced a standard threshold shift (at
least 25% if corrected for age-induced hearing loss). Further, this
commenter estimated that about 25% of the miners have an average
hearing loss of 25 dB or more at 1000, 2000, and 3000 Hz. Corrected for
age-induced hearing loss, the percentage of miners with this level of
hearing loss decreased to about 15%.
The second commenter referred to an oral presentation by Smith et
al. at the 1989 Alabama Governor's Safety and Health Conference. (MSHA
notes that the Smith presentation itself is not part of the rulemaking
record, although Smith verified that the comment was correct via letter
(December 5, 1994). MSHA believes that the Smith paper is valid
evidence which supports the rule.) This commenter stated that Smith et
al. reported on the evaluation of serial audiograms from 100 workers
exposed to sound levels less than 85 dBA. The authors found that 15% of
these workers would have some degree of hearing impairment using the
AAO-HNS 1979 definition. They also reported that at least 26% of the
mining population would have some degree of hearing impairment using
the same definition.
In response to MSHA's request for additional specific information
regarding hearing loss among miners, some commenters stated that they
had no workers' compensation awards for miners' hearing loss at their
operations. No commenters supplied information regarding the cost of
compensation awards. Some commenters supplied specific information on
miner's age, occupation, and degree of hearing loss. Several commenters
submitted data, some in conjunction with an analysis of the data, in
support of their position that hearing protectors can be effective as
the primary means of protecting miners against occupational noise-
induced hearing loss.
The NIOSH (Franks) analysis of the two databases cited by MSHA and
the three analyses conducted by Clark and Bohl under the auspices of
the National Mining Association (the first a report summarizing a
reanalysis of the NIOSH Coal Miner Study, the second a report
containing a reanalysis of the NIOSH Metal and Nonmetal Miner Study,
and the third a report containing an analysis of two data bases from
the National Mining Association) indicate that miners are developing
hearing losses to a degree that constitutes material impairment. These
analyses also indicate that the amount of hearing loss and the
percentage of the population that is impaired is highly variable.
Further, some individual miners received a substantial hearing loss.
The differences in the conclusions of these studies are attributable to
the different baselines used in the analyses for comparison of the
exposed populations. The NIOSH analysis included detailed screening of
the data and used a control group (described in Appendix A of
[[Page 49568]]
ANSI S3.44, ``American National Standard Determination of Occupational
Noise Exposure and Estimation of Noise-Induced Hearing Impairment'')
where the hearing losses of the group are strictly due to aging. In
contrast, the Clark-Bohl analyses and conclusions did not include
screening of the data and used for comparison the control group
(described in Appendix C of ANSI S3.44) where the control group's
hearing losses included those due to exposures to less than two weeks
of occupational noise, exposures to non-occupational noise, otological
abnormalities, as well as those due to aging. There is insufficient
information in the studies to allow a determination of which method of
analysis is more appropriate or superior. As a result of the
differences in approach between these analyses, the analyses arrive at
different conclusions regarding the magnitude of the hearing losses
exhibited by miners, although all of these analyses do indicate that
some miners are developing a material impairment of hearing in varying
degrees. Additionally, these analyses do not support the conclusion
that a hearing conservation program that relies primarily or
exclusively on the use of hearing protectors effectively protects all
miners from noise-induced occupational hearing loss.
Other studies and data were submitted by other commenters in
support of their position that a hearing conservation program that
relies primarily or soley on the use of hearing protectors can
adequately protect miners' hearing. These studies and data are
discussed later in the preamble.
Reported Hearing Loss Data
Under MSHA's existing regulations at 30 CFR part 50, mine operators
are required to report cases of noise-induced hearing loss to MSHA when
it is diagnosed by a physician or when the affected miner receives an
award of compensation. Between 1985 and 1997, mine operators reported a
total of 2,590 cases of noise-induced hearing loss. In a substantial
number of these cases, the occupational noise exposures occurred after
the implementation of the current noise regulations.
Coal mine operators reported 674 cases among surface miners, 1,098
cases among underground miners, and 14 cases among miners whose
positions were not identified. According to coal mine operators, 710 of
the 1,786 cases began working at a mine after the implementation of the
noise regulations for coal mines--1972 for underground coal mining and
1973 for surface coal mining. Workers with no reported mining
experience were excluded from the analysis.
Metal and nonmetal mine operators reported 650 cases among surface
miners and 154 cases among underground miners, a total of 804 cases.
According to mine operators, 172 of the 804 cases began working at a
mine after the implementation of noise regulations for metal and
nonmetal mines in 1975. Again, workers with no reported mining
experience were excluded from the analysis.
Comparing the two types of mining, there were significantly more
reported hearing loss cases at coal mines than at metal and nonmetal
mines, and a higher proportion of those cases were reported of workers
who began working after the implementation of the current standards.
This is despite the fact that, at present, there are more metal and
nonmetal miners than coal miners employed in the United States. A
possible explanation of the difference between reported cases of noise-
induced hearing loss among coal and metal and nonmetal miners may be
that there is more frequent use of engineering noise controls in metal
and nonmetal mining. Because the occupational noise standards for coal
mines allow inspectors to take into account the use of hearing
protectors in determining compliance, most coal mines use hearing
protectors for compliance unless the engineering controls are
inexpensive or come with the equipment. Metal/nonmetal mines are not
allowed to use hearing protectors for compliance unless they have
implemented all feasible engineering and administrative controls. Other
possible reasons include differences in the severity of the noise
exposures, variations among states' criteria for workers' compensation
awards, continual use of hearing protectors, and the effectiveness of
selected hearing protectors.
MSHA reviewed the narrative associated with each case of noise-
induced hearing loss to determine the average degree of hearing loss.
Although many narratives included reasons for reporting the noise-
induced hearing loss, others only listed the illness as ``hearing
loss.'' Approximately half the cases had no information on the severity
of the hearing loss. Some contained designations such as standard
threshold shift, OSHA reportable case, or percent disability. The
narratives did not contain enough information with which to determine
an average severity for cases of noise-induced hearing loss.
At least 40% of the reported cases in coal mining resulted in the
miner being compensated for noise-induced hearing loss. Another 7% of
the reported cases indicated that a workers' compensation claim for
noise-induced hearing loss had been filed. In metal and nonmetal mines,
at least 21% of the reported cases resulted from the miner being
compensated for noise-induced hearing loss. Nearly another 4% of the
reported cases indicated that a workers' compensation claim for noise-
induced hearing loss had been filed.
The low number of cases reported to the Agency are believed to be
due to either:
(1) The lack of a specific definition of a noise-induced hearing
loss in MSHA's part 50 regulations and the resulting confusion on the
part of mine operators about which cases to report;
(2) The lack of consistency among state requirements for awarding
compensation for a noise-induced hearing loss and among physicians in
diagnosing what constitutes a hearing loss caused by noise; or
(3) The lack of required periodic audiometric testing in the mining
industry.
In sum, the hearing loss currently reported to MSHA under part 50
cannot be used to accurately characterize the incidence, prevalence, or
severity of hearing loss in the mining industry. However, the data
clearly show that miners are experiencing noise-induced hearing loss.
Workers' Compensation Data
The preamble to the proposal reviewed a study by Valoski (1994) of
the number of miners receiving workers' compensation and the associated
indemnity costs of those awards. Despite contacting each state workers'
compensation agency and using two national databases, Valoski was
unable to obtain data for all states, including those with significant
mining activities. Valoski reported that between 1981 and 1985 at least
2,102 coal miners and 312 metal and nonmetal miners were awarded
compensation for occupational hearing loss. The identified total
indemnity costs of those awards exceeded $12.5 million, excluding
rehabilitation or medical costs.
In a letter to MSHA, NIOSH cited the Chan et al. (1995)
investigation for NIOSH of the incidence of noise-induced hearing loss
among miners using information from the Bureau of Labor Statistics'
(BLS) Supplementary Data System. In the 15 states that participated in
the BLS program between 1984 and 1988, a total of 217 miners (93 coal
miners and 124 metal and nonmetal miners) were awarded workers'
compensation for noise-induced hearing loss. During those
[[Page 49569]]
years, mine operators from all states reported 873 cases of noise-
induced hearing loss among coal miners and 286 cases among metal and
nonmetal miners. Chan et al. stated that because of differing state
workers' compensation requirements, it is not possible to directly
compare noise-induced hearing losses among the states. These factors
limit the usefulness of the data obtained.
MSHA reviewed reports on workers' compensation in Canada and
Australia in the preamble to the proposed rule. The noise regulations
and mining equipment used in these countries are similar to those in
the United States. A recent report on workers' compensation awards to
miners in Ontario, Canada (1991) showed that between 1985 and 1989,
noise-induced hearing loss was the second leading compensable
occupational disease. Approximately 250 claims for noise-induced
hearing loss involving miners were awarded annually during that time.
Lescouflair et al. (1980) studied 278 metal and asbestos miners
working in Quebec, Canada who claimed compensation for hearing loss.
After excluding 28.7% (80) cases of non-mining noise-induced hearing
loss, approximately 50% (99) of those diagnosed as having noise-induced
hearing loss were shown to have a hearing impairment, based on the AAOO
1959 definition. An estimated 63% (125) showed an impairment based on
AAO-HNS 1979 definition. The miners were exposed to noise for 15 to 49
years and showed a similar occurrence of hearing loss in both surface
and underground occupations. The researchers also reported that there
was no significant difference in noise-induced hearing loss between
those miners exposed to a combination of intermittent and continuous
noise and those exposed to intermittent noise, except at 2000 Hz.
Eden (1993) reported on the Australian mining industry's experience
with hearing conservation. Eden quoted statistics from the Joint Coal
Board which revealed that noise-induced hearing loss made up 59% to 80%
of the reported occupational diseases from 1982 to 1992. Eden also
reported that in New South Wales, 474 of 16,789 coal miners were
awarded compensation for noise-induced hearing loss. The incidence rate
for the total mining industry in New South Wales was about 23 cases per
1,000 workers during 1990-1991. This was the highest rate for any
industry in New South Wales.
Although the compensation data are incomplete and cannot be used
for estimating the prevalence of noise-induced hearing loss in the
mining industry, the limited data available show that numerous cases
are being filed each year, at considerable cost. Furthermore, according
to the data reported by mine operators, many miners who developed
noise-induced hearing loss worked in mining only after the
implementation of the current noise regulations. This evidence of
continued risk, although limited, supplements and supports the data
previously presented from scientific studies.
Exposures in the U.S. Mining Industry
Miners in the U.S. are at significant risk of experiencing material
impairment as a result of exposure to noise. Exposure levels remain
high in all sectors of the mining industry, even though noise
regulations have been implemented for some time. Exposures are
particularly high in the coal mining sector, where hearing protectors,
rather than engineering or administrative controls, remain the primary
means of protection against noise-induced hearing loss.
Inspection Data
Noise exposure data has been collected by MSHA inspectors from
thousands of samples gathered over many years. Table 9 indicates
samples which present readings exceeding the permissible exposure
level, (TWA8 of 90 dBA) and also shows noise dose trends in
metal and nonmetal mines based on over 232,500 full-shift samples
collected using personal noise dosimeters by MSHA from 1974 through
1997.
Table 9.--MNM Mines Noise Dose Trends CYs 1974-97 *
------------------------------------------------------------------------
Number
Number of samples Percent
Fiscal year samples exceeding exceeding
90 dBA TWA8 90 dBA TWA8
------------------------------------------------------------------------
1974............................. 363 139 38.3
1975............................. 3,826 1,661 43.4
1976............................. 9,164 3,725 40.6
1977............................. 13,485 5,047 37.4
1978............................. 17,326 6,415 37.0
1979............................. 21,176 7,638 36.1
1980............................. 15,185 5,203 34.3
1981............................. 11,278 3,651 32.4
1982............................. 3,208 876 27.3
1983............................. 7,628 2,188 28.7
1984............................. 8,525 2,311 27.1
1985............................. 8,040 2,094 26.0
1986............................. 9,213 2,402 26.1
1987............................. 10,145 2,818 27.8
1988............................. 10,514 2,417 23.0
1989............................. 10,279 2,208 21.5
1990............................. 13,067 2,721 20.8
1991............................. 14,936 2,947 19.7
1992............................. 14,622 2,809 19.2
1993............................. 14,566 2,529 17.4
1994............................. 15,979 2,627 16.4
1995............................. 13,865 1,989 14.4
1996............................. 16,686 2,228 13.4
1997............................. 10.731 1,989 14.3
------------------------------------------------------------------------
* From USBM's MIDAS data base. Italicized data not included in chart 9a.
[[Page 49570]]
Table 10 shows samples with readings exceeding the permissible
exposure level (TWA8 of 90 dBA) and noise dose trends in
coal mines based on 75,691 full-shift samples collected by MSHA from
1986 through 1997 using personal noise dosimeters. MSHA began routine
sampling in coal mines in 1978 but did not begin building the database
until 1986.
Table 10.--Coal Mine Noise Dose Trends, FYs 86-97
------------------------------------------------------------------------
Number
Number of samples Percent
Fiscal year samples exceeding exceeding
90 dBA TWA8 90 dBA TWA8
------------------------------------------------------------------------
1986............................. 2,037 593 29.1
1987............................. 12,774 3,314 25.9
1988............................. 11,888 2,702 22.7
1989............................. 11,035 2,313 21.0
1990............................. 10,861 2,388 22.0
1991............................. 6,898 1,635 23.7
1992............................. 6,636 1,660 25.0
1993............................. 7,223 1,908 26.4
1994............................. 6,339 1,656 26.1
1995............................. 5,407 1,219 22.5
1996............................. 6,064 1,256 20.7
1997............................. 6,542 1,388 21.2
------------------------------------------------------------------------
The inspection data for the coal and metal and nonmetal mining
sectors have been graphed in Charts 9a and 10a, which indicate that the
metal and nonmetal sector shows a gradual but consistent downward trend
in the percentage of samples exceeding the current permissible exposure
level. However, there was no such clear trend for coal mines during the
same period. MSHA attributes this difference to the established use of
engineering and administrative controls in metal and nonmetal mines.
[[Page 49571]]
[GRAPHIC] [TIFF OMITTED] TR13SE99.004
MSHA notes that the interaction of two factors in the data
represented in these charts may offset each other. First, the database
is made up of samples collected in noisier mines and occupations.
Second, the database includes both initial overexposure and the results
of any resampling to determine compliance after the mine operator has
utilized engineering or administrative controls (in the case of an
overexposure found during an initial survey).
Dual Survey Data
MSHA conducted a special survey to compare noise exposures at
different threshold levels, because the final rule requires integration
of sound levels between 80 dBA and at least 130 dBA for the action
level and between 90 dBA and at least 140 dBA for the permissible
exposure level. The survey, referred to as the dual-threshold survey,
involved the collection by MSHA inspectors of data in coal, metal, and
nonmetal mines. Each sample was collected using a personal noise
dosimeter capable of collecting data at both thresholds simultaneously.
All other dosimeter settings were the same as those used during normal
compliance inspections (the 90 dBA criterion level, 5-dB exchange rate,
and A-weighting and slow response characteristics). The noise doses
were mathematically converted to their corresponding TWA8.
Tables 11 and 12 display the dual-threshold data in metal and
nonmetal mines and in coal mines. Table 11 shows the dual-threshold
data collected for metal and nonmetal mines from March 1991 through
December 1994 using personal noise dosimeters. This data consisted of
more than 42,000 full-shift samples.
Table 11.--M/NM Dual-Threshold Noise Samples Equal to or Exceeding Specified TWA8 Sound Levels--March 1991
through December 1994
----------------------------------------------------------------------------------------------------------------
90 dBA threshold 80 dBA threshold
---------------------------------------------------
TWA8 sound level (in dBA) Number of Percent of Number of Percent of
samples samples samples samples
----------------------------------------------------------------------------------------------------------------
90 (PEL).................................................... 7,360 17.4 ........... ...........
[[Page 49572]]
85 (action level)........................................... ........... ........... 28,250 66.9
----------------------------------------------------------------------------------------------------------------
As indicated in Table 11, 17.4% of all samples collected by MSHA in
metal and nonmetal mines during the specified period equaled or
exceeded the permissible exposure level (a TWA 8 of 90 dBA
using a 90-dBA threshold)--slightly less than the results of the
inspectors' samplings in Table 9. Under the final rule feasible
engineering and administrative controls are required to be implemented
in such instances in all mines to reduce the noise exposure to the
permissible exposure level. Furthermore, 67% of the samples in metal
and nonmetal mines exceeded the action level (a TWA8 of 85
dBA using an 80-dBA threshold).
MSHA's dual-threshold sampling data for coal mines is presented in
Table 12. These data consist of over 4,200 full-shift samples collected
from March 1991 through December 1995 using personal noise dosimeters.
Table 12.--Coal Dual-Threshold Noise Samples Equal to or Exceeding Specified TWA8 Sound Levels
[March 1991 Through December 1995]
----------------------------------------------------------------------------------------------------------------
90 dBA threshold 80 dBA threshold
---------------------------------------------------
TWA8 sound level (in dBA) Number of Percent of Number of Percent of
samples samples samples samples
----------------------------------------------------------------------------------------------------------------
90 (PEL).................................................... 1,075 25.3 ........... ...........
85 (action level)........................................... ........... ........... 3,268 76.9
----------------------------------------------------------------------------------------------------------------
As indicated in Table 12, 25.3% of all samples collected by MSHA in
coal mines during the specified period equaled or exceeded the
permissible exposure level (a TWA8 of 90 dBA using a 90-dBA
threshold). Furthermore, almost 77% of the survey samples from the coal
industry showed noise exposures equaling or exceeding a TWA8
of 85 dBA using an 80-dBA threshold (the action level).
Tables 13 and 14 present some of the MSHA dual-threshold sampling
data by occupation for the most frequently sampled occupations in metal
and nonmetal and coal mines, respectively.
Table 13.--Percentage of MSHA M/NM Inspector Noise Samples Exceeding Specified TWA8 Sound Levels, by Selected
Occupation
----------------------------------------------------------------------------------------------------------------
90 dBA 80 dBA
threshold threshold
-------------------------------
Number of Percent of
Occupation samples Percent of samples 90 thn-eq>85 dBA
dBA (PEL) (action level)
----------------------------------------------------------------------------------------------------------------
Front-End-Loader Operator....................................... 12,812 12.9 67.7
Truck Driver.................................................... 6,216 13.1 73.7
Crusher Operator................................................ 5,357 19.9 65.1
Bulldozer Operator.............................................. 1,440 50.7 86.2
Bagger.......................................................... 1,308 10.2 65.0
Sizing/Washing Plant Operator................................... 1,246 13.2 59.7
Dredge/Barge Attendant.......................................... 1,124 27.2 78.7
Clean-up Person................................................. 927 19.3 71.3
Dry Screen Operator............................................. 871 11.7 57.6
Utility Worker.................................................. 846 12.4 60.6
Mechanic........................................................ 761 3.8 43.9
Supervisors/Administrators...................................... 730 9.0 32.2
Laborer......................................................... 642 17.1 65.7
Dragline Operator............................................... 583 34.0 82.5
Backhoe Operator................................................ 546 8.4 52.6
Dryer/Kiln Operator............................................. 517 10.5 55.5
Rotary Drill Operator (electric/hydraulic)...................... 543 39.6 83.1
Rotary Drill Operator (pneumatic)............................... 489 64.4 89.0
----------------------------------------------------------------------------------------------------------------
These occupations comprise about 87 percent of the 42,206 MSHA dual-threshold samples collected at
metal/nonmetal mines from March 1991 through December 1994 using a personal noise dosimeter over a miner's
full shift
[[Page 49573]]
Table 14.--Percentage of MSHA Coal Inspector Noise Samples Exceeding Specified TWA8 Sound Levels, by Selected
Occupation
----------------------------------------------------------------------------------------------------------------
90 dBA 80 dBA
threshold threshold
-------------------------------
Number of Percent of
Occupation samples Percent of samples 90 thn-eq>85 dBA
dBA (PEL) (action level)
----------------------------------------------------------------------------------------------------------------
Continuous Miner Helper......................................... 68 33.8 88.2
Continuous Miner Operator....................................... 262 49.6 96.2
Roof Bolter Operator (Single)................................... 234 21.8 85.5
Roof Bolter Operator (Twin)..................................... 92 31.5 98.9
Shuttle Car Operator............................................ 260 13.5 78.5
Scoop Car Operator.............................................. 94 18.1 74.5
Cutting Machine Operator........................................ 22 36.4 63.6
Headgate Operator............................................... 20 40.0 100.0
Longwall Operator............................................... 34 70.6 100.0
Jack Setter (Longwall).......................................... 25 32.0 68.0
Cleaning Plant Operator......................................... 107 36.4 77.6
Bulldozer Operator.............................................. 225 48.9 94.2
Front-End-Loader Operator....................................... 244 16.0 76.6
Highwall Drill Operator......................................... 83 21.7 77.1
Refuse/Backfill Truck Driver.................................... 162 13.6 78.4
Coal Truck Driver............................................... 28 17.9 64.3
----------------------------------------------------------------------------------------------------------------
These occupations comprise about 71 percent of the 4,247 MSHA dual-threshold samples collected at coal
mine from March 1991 to December 1995 using a personal noise dosimeter over a miner's full shift
As shown in these tables, the percentage of miners exceeding the
specified noise exposures varied greatly according to occupation. For
example, Table 13 shows that only 8.4% of the backhoe operators in
metal and nonmetal mines had noise exposures exceeding the permissible
exposure level, while 64.4% of the pneumatic rotary drill operators had
similar exposures. 52.6% of the backhoe operators and 89.0% of the
pneumatic rotary drill operators would have noise exposures exceeding
the action level.
Conclusion: Miners at Significant Risk of Material Impairment
MSHA has concluded that, despite many years under existing
standards, noise exposures in all sectors of mining continue to pose a
significant risk of material impairment to miners over a working
lifetime. Specifically, MSHA estimates in the REA that 14% of coal
miners (13,294 miners) will incur a material impairment of hearing
under present exposure conditions.
Table 15 presents MSHA's profile of the projected number of miners
currently subjected to a significant risk of developing a material
impairment due to occupational noise-induced hearing loss under
existing exposure conditions. The totals represent 13% of metal and
nonmetal miners and 13.4% of miners as a whole.
Table 15.--Projected Number of Miners Likely to Incur Noise-Induced Hearing Impairment Under MSHA's Existing Standards and Exposure Conditions
--------------------------------------------------------------------------------------------------------------------------------------------------------
100-104.99 105
<80 dba="" 80-84.9="" dba="" 85-89.9="" dba="" 90-94.9="" dba="" 95-99.9="" dba="" dba="" dba="" total*="" --------------------------------------------------------------------------------------------------------------------------------------------------------="" coal.........................................="" 0="" 464="" 10,954="" 1,315="" 456="" 104="" 1="" 13,294="" m/nm.........................................="" 0="" 1,091="" 15,472="" 6,030="" 1,002="" 48="" 0="" 23,643="" ----------------------------------------------------------------------------------------------------------="" total*...................................="" 0="" 1,555="" 26,426="" 7,345="" 1,458="" 152="" 1="" 36,937="" --------------------------------------------------------------------------------------------------------------------------------------------------------="" *="" includes="" contractor="" employees.="" does="" not="" include="" office="" workers.="" discrepancies="" are="" due="" to="" rounding.="" msha="" promulgated="" noise="" standards="" for="" underground="" coal="" mines="" in="" 1971,="" for="" surface="" coal="" mines="" in="" 1972,="" and="" for="" metal="" and="" nonmetal="" mines="" in="" 1974.="" at="" that="" time,="" the="" agency="" regarded="" compliance="" with="" the="" requirements="" as="" adequate="" to="" prevent="" the="" occurrence="" of="" noise-induced="" hearing="" loss="" in="" the="" mining="" industry.="" since="" that="" time,="" however,="" there="" have="" been="" numerous="" awards="" of="" compensation="" for="" hearing="" loss="" among="" miners.="" moreover,="" in="" light="" of="" msha's="" experience="" and="" that="" of="" other="" domestic="" and="" foreign="" regulatory="" agencies,="" as="" well="" as="" expert="" opinion="" on="" what="" constitutes="" an="" effective="" prevention="" program,="" the="" agency's="" requirements="" are="" dated.="" niosh,="" for="" example,="" currently="" recommends="" a="" comprehensive="" program="" which="" includes="" the="" institution="" of="" a="" hearing="" conservation="" program="" to="" prevent="" noise-induced="" hearing="" loss,="" but="" msha's="" current="" standards="" do="" not="" include="" such="" protection.="" some="" commenters="" suggested="" that="" the="" existing="" standards="" adequately="" protect="" miners="" against="" noise-induced="" hearing="" loss="" and="" that="" msha="" over-="" estimates="" the="" hazard.="" however,="" the="" vast="" majority="" of="" the="" current="" scientific="" evidence="" demonstrates="" that="" noise-induced="" hearing="" loss="" constitutes="" a="" serious="" hazard="" to="" miners.="" msha's="" experience="" in="" enforcing="" its="" existing="" standards="" bears="" this="" out,="" necessitating="" the="" replacement="" of="" those="" standards="" with="" new="" ones="" that="" would="" provide="" additional="" protection="" to="" miners="" consistent="" with="" section="" 101(a)(6)(a)="" of="" the="" federal="" mine="" safety="" and="" health="" act="" of="" 1977="" (mine="" act),="" which="" states="" that="" msha's="" promulgation="" of="" health="" standards="" must:="" *="" *="" *="" [a]dequately="" assure="" on="" the="" basis="" of="" the="" best="" available="" evidence="" that="" no="" miner="" will="" [[page="" 49574]]="" suffer="" material="" impairment="" of="" health="" or="" functional="" capacity="" even="" if="" such="" miner="" has="" regular="" exposure="" to="" the="" hazards="" dealt="" with="" by="" such="" standard="" for="" the="" period="" of="" his="" working="" life.="" based="" on="" the="" numerous="" studies="" and="" msha's="" calculations="" and="" analysis="" presented="" above,="" the="" agency="" has="" concluded="" that="" the="" new="" requirements="" in="" this="" rule="" are="" necessary="" to="" address="" the="" continued="" excess="" risk="" of="" material="" impairment="" due="" to="" occupational="" noise-induced="" hearing="" loss.="" compliance="" will="" reduce="" noise-induced="" hearing="" loss="" among="" miners,="" as="" well="" as="" the="" associated="" workers'="" compensation="" costs.="" the="" new="" rule="" provides="" the="" added="" benefit="" of="" making="" msha's="" noise="" rule="" consistent="" with="" osha's="" noise="" standard="" for="" general="" industry,="" as="" recommended="" by="" many="" commenters.="" vi.="" feasibility="" section="" 101(a)(6)(a)="" of="" the="" mine="" act="" requires="" the="" secretary="" to="" set="" standards="" which="" most="" adequately="" assure,="" on="" the="" basis="" of="" the="" best="" available="" evidence,="" that="" no="" miner="" will="" suffer="" material="" impairment="" of="" health="" or="" functional="" capacity="" over="" his="" or="" her="" working="" lifetime.="" standards="" promulgated="" under="" this="" section="" must="" be="" based="" upon="" research,="" demonstrations,="" experiments,="" and="" such="" other="" information="" as="" may="" be="" appropriate.="" msha,="" in="" setting="" health="" standards,="" is="" required="" to="" achieve="" the="" highest="" degree="" of="" health="" and="" safety="" protection="" for="" the="" miner,="" and="" must="" consider="" the="" latest="" available="" scientific="" data="" in="" the="" field,="" the="" feasibility="" of="" the="" standards,="" and="" experience="" gained="" under="" this="" and="" other="" health="" and="" safety="" laws.="" in="" relation="" to="" promulgating="" health="" standards,="" the="" legislative="" history="" of="" the="" mine="" act="" states="" that:="" this="" section="" further="" provides="" that="" ``other="" considerations''="" in="" the="" setting="" of="" health="" standards="" are="" ``the="" latest="" available="" scientific="" data="" in="" the="" field,="" the="" feasibility="" of="" the="" standards,="" and="" experience="" gained="" under="" this="" and="" other="" health="" and="" safety="" laws.''="" while="" feasibility="" of="" the="" standard="" may="" be="" taken="" into="" consideration="" with="" respect="" to="" engineering="" controls,="" this="" factor="" should="" have="" a="" substantially="" less="" significant="" role.="" thus,="" the="" secretary="" may="" appropriately="" consider="" the="" state="" of="" the="" engineering="" art="" in="" industry="" at="" the="" time="" the="" standard="" is="" promulgated.="" however,="" as="" the="" circuit="" courts="" of="" appeals="" have="" recognized,="" occupational="" safety="" and="" health="" statutes="" should="" be="" viewed="" as="" ``technology-forcing''="" legislation,="" and="" a="" proposed="" health="" standard="" should="" not="" be="" rejected="" as="" infeasible="" ``when="" the="" necessary="" technology="" looms="" in="" today's="" horizon''.="" afl-cio="" v.="" brennan,="" 530="" f.2d="" 109)="" (3d="" cir.="" 1975);="" society="" of="" plastics="" industry="" v.="" osha,="" 509="" f.2d="" 1301="" (2d="" cir.="" 1975)="" cert.="" den.="" 427="" u.s.="" 992="" (1975).="" similarly,="" information="" on="" the="" economic="" impact="" of="" a="" health="" standard="" which="" is="" provided="" to="" the="" secretary="" of="" labor="" at="" a="" hearing="" or="" during="" the="" public="" comment="" period,="" may="" be="" given="" weight="" by="" the="" secretary.="" in="" adopting="" the="" language="" of="" [this="" section],="" the="" committee="" wishes="" to="" emphasize="" that="" it="" rejects="" the="" view="" that="" cost="" benefit="" ratios="" alone="" may="" be="" the="" basis="" for="" depriving="" miners="" of="" the="" health="" protection="" which="" the="" law="" was="" intended="" to="" insure.="" s.="" rep.="" no.="" 95-181,="" 95th="" cong.,="" 1st="" sess.="" 21="" (1977).="" in="" american="" textile="" manufacturers'="" institute="" v.="" donovan,="" 452="" u.s.="" 490,="" 508-509="" (1981),="" the="" supreme="" court="" defined="" the="" word="" ``feasible''="" as="" ``capable="" of="" being="" done,="" executed,="" or="" effected.''="" the="" court="" further="" stated,="" however,="" that="" a="" standard="" would="" not="" be="" considered="" economically="" feasible="" if="" an="" entire="" industry's="" competitive="" structure="" were="" threatened.="" in="" promulgating="" standards,="" hard="" and="" precise="" predictions="" from="" agencies="" regarding="" feasibility="" are="" not="" required.="" the="" ``arbitrary="" and="" capricious="" test''="" is="" usually="" applied="" to="" judicial="" review="" of="" rules="" issued="" in="" accordance="" with="" the="" administrative="" procedures="" act.="" the="" legislative="" history="" of="" the="" mine="" act="" indicates="" that="" congress="" explicitly="" intended="" the="" ``arbitrary="" and="" capricious="" test''="" be="" applied="" to="" judicial="" review="" of="" mandatory="" msha="" standards.="" ``this="" test="" would="" require="" the="" reviewing="" court="" to="" scrutinize="" the="" secretary's="" action="" to="" determine="" whether="" it="" was="" rational="" in="" light="" of="" the="" evidence="" before="" him="" and="" reasonably="" related="" to="" the="" law's="" purposes.="" *="" *="" *''="" s.="" rep.="" no.="" 95-181,="" 95th="" cong.,="" 1st="" sess.="" 21="" (1977).="" thus,="" msha="" need="" only="" base="" its="" predictions="" on="" reasonable="" inferences="" drawn="" from="" the="" existing="" facts.="" accordingly,="" to="" establish="" the="" economic="" and="" technological="" feasibility="" of="" a="" new="" rule,="" an="" agency="" is="" required="" to="" produce="" a="" reasonable="" assessment="" of="" the="" likely="" range="" of="" costs="" that="" a="" new="" standard="" will="" have="" on="" an="" industry,="" and="" the="" agency="" must="" show="" that="" a="" reasonable="" probability="" exists="" that="" the="" typical="" firm="" in="" an="" industry="" will="" be="" able="" to="" develop="" and="" install="" controls="" that="" will="" meet="" the="" standard.="" technological="" feasibility="" msha="" has="" determined="" that="" a="" permissible="" exposure="" level="" of="" a="">8 of 90 dBA is technologically feasible for the mining
industry. An agency must show that modern technology has at least
conceived some industrial strategies or devices that are likely to be
capable of meeting the standard, and which industry is generally
capable of adopting. American Iron and Steel Institute v. OSHA, (AISI-
II) 939 F.2d 975, 980 (D.C. Cir. 1991); American Iron and Steel
Institute v. OSHA, (AISI-I) 577 F.2d 825 (3d Cir. 1978) at 832-835; and
Industrial Union Dep't., AFL-CIO v. Hodgson, 499 F.2d 467 (D.C. Cir.
1974). The Secretary may also impose a standard that requires
protective equipment, such as respirators, if technology does not exist
to lower exposure to safe levels. See United Steelworkers of America,
AFL-CIO-CLC v. Marshall, 647 F.2d 1189, 1266 (D.C. Cir. 1981).
The Agency has vast experience in working with the mining community
in continually refining and improving existing noise control
technology. At the request of MSHA's Coal Mine Safety and Health or
Metal and Nonmetal Mine Safety and Health, MSHA's Technical Support
staff actively assists mine operators in developing effective noise
controls. Based on this experience, the Agency has concluded that there
are few circumstances in mining where such controls do not exist.
MSHA acknowledges that some mining equipment historically has
presented technological feasibility challenges for the mining industry.
However, MSHA has evaluated, under actual mining conditions, newly
developed noise controls for surface self-propelled equipment,
underground diesel-powered haulage equipment, jumbo drills, track
drills, hand-held percussive drills, draglines/shovels, portable
crushers, channel burners, and mills, and has found them to be
effective in producing a significant reduction in a miner's noise
exposure. Some of these feasible engineering controls are already
designed into new equipment. In many cases, effective and feasible
controls are available through retrofitting or the proper use of noise
barriers.
Several commenters in the metal and nonmetal sector of the mining
industry expressed concern regarding the technological and economic
feasibility of controls for their particular operations. In Volume IV
of MSHA's Program Policy Manual, which covers an interpretation,
application, and guidelines on enforcement of MSHA's existing noise
standards in metal and nonmetal mines, the Agency includes a list of
feasible noise engineering controls for the major classifications of
equipment used in the metal and nonmetal mining industry. The Agency
intends to continue applying its existing guidelines on enforcement of
the permissible exposure level in the final rule because the
permissible exposure level is unchanged from the existing standards.
MSHA, therefore, encourages mine operators to use this list so they
will be knowledgeable of available noise control technology.
[[Page 49575]]
Acoustically Treated Cabs
For mining equipment such as haul trucks, front-end-loaders,
bulldozers, track drills, and underground jumbo drills, acoustically
treated cabs are among the most effective noise controls. Such cabs are
widely available, both from the original equipment manufacturer and the
manufacturers of retrofit cabs, for machines manufactured within the
past 25 years. Today, most manufacturers include an acoustically
treated cab as part of the standard equipment on the newest pieces of
mobile mining equipment. The noise reduction of factory-installed,
acoustically treated cabs is generally more effective and often less
costly than that of retrofit cabs. According to some manufacturers,
sound levels at the machine operator's position inside factory cabs are
often below 90 dBA and, in some cases, below 85 dBA.
Additionally, environmentally controlled operator's cabs have the
added advantages of reducing dust exposure, heat stress, and ergonomic-
related hazards.
Occasionally, underground mining conditions are such that full-
sized surface haulage equipment can be used. Where this is possible,
such equipment can be equipped with a cab as described above.
These engineering noise controls are not new technology. The former
United States Bureau of Mines (USBM) published two manuals entitled
``Bulldozer Noise Controls'' (1980) and ``Front-End Loader Noise
Controls'' (1981) which describe in detail installations of retrofit
cabs and acoustical materials.
Barrier Shields
For some equipment, generally over 25 years old, an environmental
cab may not be available from the original equipment manufacturer or
from manufacturers of retrofit cabs. In such cases, a partial barrier
with selective placement of acoustical material can usually be
installed at nominal cost to block the noise reaching the equipment
operator. These techniques are demonstrated in ``Bulldozer Noise
Controls'' (1980).
Barrier shields and partial enclosures can also be used on track
drills where full cabs are infeasible. Such shields and enclosures can
be either freestanding or attached to the drill. Typically, however,
they are not as effective as cabs and usually do not reduce the miner's
noise exposure to the TWA8 of 90 dBA permissible exposure
level. This barrier can be constructed at minimal cost from used
conveyor belting and other materials found at the mine site.
Exhaust Mufflers
Diesel-powered machinery can be equipped with an effective exhaust
muffler in addition to an environmental cab or barrier shield. The
muffler's exhaust pipe can be relocated away from the equipment
operator and the emissions can be redirected away from the operator.
For underground mining equipment, exhaust mufflers are ordinarily not
needed where water scrubbers are used. A water scrubber offers some
noise reduction, but the addition of an exhaust muffler may create
excessive back pressure or interfere with the proper functioning of the
scrubber. Exhaust mufflers can, however, be installed on underground
equipment where catalytic converters are used.
Exhaust mufflers can also be installed on pneumatically powered
equipment. For example, exhaust mufflers are offered by the
manufacturers of almost every jackleg drill, chipping hammer, and jack
hammer. In the few cases where such exhaust mufflers are not available
from the original equipment manufacturer, they can be easily
constructed by the mine operator. MSHA has a videotape available to the
mining community showing the construction of such an exhaust muffler
for a jackleg drill. This muffler can be constructed at minimal cost
from a section of rubber motorcycle tire.
Acoustical Materials
Various types of acoustical materials can be strategically used for
blocking, absorbing, and/or damping sound and vibration. Damping
vibration reduces the generated sound field. Generally such materials
are installed on the inside walls of equipment cabs or operator
compartments, and in control rooms and booths. Barrier and absorptive
materials can be used to reduce noise emanating from the engine and
transmission compartments, and acoustical material can be applied to
the firewall between the employee and transmission compartment. Noise
reduction varies depending upon the specific application. Care must be
taken to use acoustical materials that will not create a fire hazard or
emit toxic fumes if exposed to heat.
Control Rooms and Booths
Acoustically treated control rooms and booths are frequently used
in mills, processing plants, or at portable operations to protect
miners from noise created by crushing, screening, or processing
equipment. Such control rooms and booths are typically successful in
reducing exposures of employees working in them to below 85 dBA.
In addition, remote controlled video cameras can be used to provide
visual observation of screens, crushing equipment, or processing
equipment, minimizing the need for a miner to be near these loud noise
sources.
Substitution of Equipment
In the few cases where sound levels are particularly severe and
neither retrofit nor factory controls are available, the equipment may
need to be replaced with a type that produces less noise. For example,
hand-held channel burners were used for many years in the mining
industry to cut granite in dimension stone quarries. Sound levels
typically exceeded 120 dBA at the operator's ear. Several years ago,
however, alternative and quieter methods of cutting granite, such as
high pressure water jet technology, automated channel burners, and
diamond wire saws, were developed in the dimension stone industry.
Dimension stone operators were notified by MSHA of the availability of
these alternatives and given time to phase out the use of diesel-
fueled, hand-held burners and replace them with one of the quieter and
more protective alternatives.
New Equipment Design
Hand-held channel burners can be replaced with automated channel
burners supplied with liquid oxygen. The automated design does not
require the operator to be near the channel burner, thereby using
distance to attenuate the noise.
The MSHA document entitled, ``Summary of Noise Controls for Mining
Machinery,'' (Marraccini et al., 1986) provides case histories of
effective noise controls installed on specific makes and models of
mining equipment. The case histories describe the controls used, their
cost, and the amount of noise reduction achieved. In particular, these
include engineering noise control methods for coal cutting equipment,
longwall equipment, conveyors, and diesel equipment. Underground coal
mining equipment may require some unique noise controls. However, for
coal extracting machines such as continuous miners and longwall
shearers, the use of remote control is the single most effective noise
control. The installation of noise damping materials and enclosure of
motors and gear cases can be used to aid in controlling noise of coal
transporting equipment such as conveyors and belt systems. Diesel
[[Page 49576]]
equipment used underground can be equipped with controls similar to
those used on surface equipment. Mufflers, sound controlled cabs, and
barriers will provide much of the needed noise control for this type of
equipment. MSHA has found that the controls utilized in these specific
cases can be extended to other pieces of mining equipment. The Agency
is currently updating this publication, and plans to reissue it at a
later date in order to assist mine operators in complying with the
requirements of the final rule.
Economic Feasibility
MSHA has determined that a permissible exposure level of a
TWA8 of 90 dBA is economically feasible for the mining
industry. Economic feasibility does not guarantee the continued
existence of individual employers. It would not be inconsistent with
the Act to have a company which turned a profit by lagging behind the
rest of an industry in providing for the health and safety of its
workers to consequently find itself financially unable to comply with a
new standard; see, United Steelworkers, 647 F.2d at 1265. Although it
was not Congress' intent to protect workers by putting their employers
out of business, the increase in production costs or the decrease in
profits would not be enough to strike down a standard. Industrial Union
Dep't., 499 F.2d at 477. Conversely, a standard would not be considered
economically feasible if an entire industry's competitive structure
were threatened. Id. at 478; see also, AISI-II, 939 F.2d at 980; United
Steelworkers, 647 F.2d at 1264-65; AISI-I, 577 F.2d at 835-36. This
would be of particular concern in the case of foreign competition, if
American companies were unable to compete with imports or substitute
products. The cost to government and the public, adequacy of supply,
questions of employment, and utilization of energy may all be
considered.
MSHA has determined that retention of the existing permissible
exposure level, threshold, and exchange rate under the final standard
would not result in any incremental costs for engineering controls for
the metal and nonmetal sector and would result in annualized costs of
$1.6 million for the coal mining sector. As described in more detail in
the Agency's final Regulatory Economic Analysis, MSHA evaluated various
engineering controls and their related costs.
In determining which engineering controls the metal and nonmetal
industry will have to use under the final rule, MSHA considered the
engineering controls that are used under the current rule. MSHA expects
that there will be no significant change because the requirements for
meeting the permissible exposure level are the same. For the coal
industry, however, MSHA expects the cost to differ significantly. Under
the current coal standards, personal hearing protectors have typically
been substituted for engineering and administrative controls;
therefore, the industry has not exhausted the use of feasible controls
capable of significantly reducing sound levels. Accordingly, the coal
sector is projected to experience relatively higher costs for
engineering controls under the final rule than the metal and nonmetal
sector.
MSHA believes the requirements for engineering and administrative
controls clearly meet the feasibility requirements of the Mine Act, its
legislative history, and related case law. The most convincing evidence
that the final rule will be economically feasible for the mining
industry as a whole is the fact that the total cost of the final rule
borne by the mining industry, $8.7 million annually, is only 0.01
percent of annual industry revenues of approximately $59.7 billion.
Nevertheless, MSHA recognizes that, in a few cases, individual mine
operators, particularly small operators, may have difficulty in
achieving full compliance with the final rule immediately because of a
lack of financial resources to purchase and install engineering
controls. However, ultimate compliance with the final rule is expected
to be achieved.
Whether controls are feasible for individual mine operators is
based in part upon legal guidance from the Federal Mine Safety and
Health Review Commission (Commission). According to the Commission, a
control is feasible when it: (1) Reduces exposure; (2) is economically
achievable; and (3) is technologically achievable. See Secretary of
Labor v. A.H. Smith, 6 FMSHRC 199 (1984); Secretary of Labor v.
Callanan Industries, Inc., 5 FMSHRC 1900 (1983).
In determining the technological feasibility of an engineering
control, the Commission has ruled that a control is deemed achievable
if, through reasonable application of existing products, devices, or
work methods, with human skills and abilities, a workable engineering
control can be applied to the noise source. The control does not have
to be ``off-the-shelf,'' but it must have a realistic basis in present
technical capabilities.
In determining the economic feasibility of an engineering control,
the Commission has ruled that MSHA must assess whether the costs of the
control are disproportionate to the ``expected benefits,'' and whether
the costs are so great that it is irrational to require its use to
achieve those results. The Commission has expressly stated that cost-
benefit analysis is unnecessary in order to determine whether a noise
control is required.
Consistent with Commission case law, MSHA considers three factors
in determining whether engineering controls are feasible at a
particular mine: (1) The nature and extent of the overexposure; (2) the
demonstrated effectiveness of available technology; and (3) whether the
committed resources are wholly out of proportion to the expected
results. A violation under the final standard would entail MSHA
determining that a miner has been overexposed, that controls are
feasible, and that the mine operator failed to install or maintain such
controls. According to the Commission, an engineering control may be
feasible even though it fails to reduce exposure to permissible levels
contained in the standard, as long as there is a significant reduction
in a miner's exposure. Todilto Exploration and Development Corporation
v. Secretary of Labor, 5 FMSHRC 1894, 1897 (1983). MSHA intends to
continue its longstanding policy of determining that a control is
feasible where a control or a combination of controls could achieve a
3-dBA noise reduction, which represents at least a 50% reduction in
sound energy. Where any single control does not provide at least a 3-
dBA noise reduction, mine operators must consider the reduction
achieved by a combination of all available controls.
Some commenters were uncertain as to whether MSHA's policy referred
to a 3-dBA reduction in sound level or a 3-dBA reduction in a miner's
noise exposure. Exposure and sound level are not synonymous terms
because an exposure includes a time factor. MSHA has determined that a
3-dBA reduction in a miner's exposure is the relevant factor in
determining feasibility. This is true because the permissible exposure
level is a personal exposure standard, which can be controlled using
engineering and administrative controls. MSHA chose a 3-dBA reduction
because accuracy of the current noise measurement instrumentation is 2
dBA, a control would not be deemed effective until the measured
reduction exceeds the accuracy of the instrumentation. The 3-dBA
reduction in a miner's exposure is different from and should not be
confused with the discussion of the exchange rate in this preamble.
[[Page 49577]]
The Agency is cognizant that there may be instances where all
feasible engineering and administrative controls have been used and a
miner's noise exposure cannot be reduced to the permissible exposure
level. Under those circumstances, in both the coal and metal and
nonmetal sectors, MSHA intends to enforce the final rule consistent
with its current p code policy for metal and nonmetal mines.
Currently, when MSHA issues a citation for a noise overexposure,
the operator must use all feasible engineering and administrative
controls to bring noise exposures within the permissible level. Under
current MSHA policy where feasible engineering or administrative
controls have failed to lower noise exposures to a permissible level at
a metal or nonmetal mine, the citation may be terminated on the
condition that personal protective equipment is provided and worn. This
type of termination, referred to as a ``P'' code, is permitted after
certain procedures have been followed.
If the District Manager where the citation was issued believes a
``P'' code is warranted, the Manager reviews the situation in
consultation with field enforcement staff, headquarters officials, and
MSHA technical experts. This review includes an evaluation of the
circumstances surrounding the overexposure, with particular emphasis on
assessing the feasibility and effectiveness of control options.
If the reviewers determine that a ``P'' code is appropriate, the
citation will be terminated and the termination will state the minimum
acceptable performance requirements for hearing protectors, and the
minimum acceptable engineering and administrative controls that must be
used in conjunction with the hearing protectors. After a ``P'' code has
been issued, MSHA provides the National Institute for Occupational
Safety and Health (NIOSH) a copy of the associated technical
documentation to alert researchers of the specific instances of noise
overexposures where noise exposures cannot be reduced to permissible
levels using feasible engineering or and administrative controls. SHA
considers both technological capabilities and the economic impact of a
control.
MSHA regularly reviews those instances where ``P'' codes have been
issued to determine whether conditions have changed or new technology
is available to warrant reconsidering the justification for the ``P''
code. MSHA may withdraw the ``P'' code if the original justification
for the ``P'' code is no longer valid. The decision may be based on
such factors as a change in operating conditions, new technology, or
failure of the mine operator to comply with the specified control
measures.
VII. Section-by-Section Analysis
Section 62.100 Purpose and Scope; Effective Date
The purpose of the mandatory health standard established in part 62
is to prevent the occurrence and reduce the progression of occupational
noise-induced hearing loss among miners in every surface and
underground metal, nonmetal, and coal mine subject to the Federal Mine
Safety and Health Act of 1977.
The final rule establishes a single uniform noise standard
applicable to all mines. Most commenters favored the one-rule format,
agreeing with the Agency that consolidation and simplification of the
existing multiple standards may help to facilitate understanding of,
and thus compliance with, regulatory requirements.
Prior to this final rule, MSHA had four sets of noise standards:
for surface metal and nonmetal mines (30 CFR 56.5050), for underground
metal and nonmetal mines (30 CFR 57.5050), for underground coal mines
(30 CFR part 70, subpart F), and for surface coal mines and surface
work areas of underground coal mines (30 CFR part 71, subpart I). The
surface and underground noise standards for metal and nonmetal mines
were identical, and the surface and underground noise standards for
coal mines were nearly identical.
MSHA was influenced by several factors in deciding to promulgate
this final rule: the prevalence of hearing loss among miners despite
experience with the current standard, conditions in the mining
industry, MSHA's review of the latest scientific information, the
comments submitted in response to the proposed rule, and the
requirements of the Mine Act.
The rule contains provisions that are consistent with many of
OSHA's requirements yet tailored to meet the specific needs of the
mining community. In addition, many of the provisions are similar, if
not identical, to the existing MSHA noise standards, which will allow
for continuity in the transition to the new rule.
The final rule takes effect one year after the date of publication.
MSHA recognizes that successful implementation of the final rule
requires training of MSHA personnel and guidance to miners and mine
operators, particularly small mine operators. Therefore, in response to
several supportive comments, the Agency has decided that this delayed
effective date best meets the needs of the mining community.
Section 62.101 Definitions
The definitions discussed below are included in the final rule to
facilitate understanding of technical terms that are used in this part.
Some of the proposed definitions have been revised to be consistent
with the common usage of such terms. For example, the Agency's proposed
use of the term ``supplemental baseline audiogram'' has been changed to
the more commonly used ``revised baseline audiogram.''
The final rule also includes a definition for action level. MSHA
moved the definition of action level from the text of the proposed rule
and included it in the definition section of the final rule to be
consistent with the terms permissible exposure level and dual hearing
protection level which are in the definition section. In addition, on
the suggestion of several commenters who expressed confusion over the
use of the proposed term ``designated representative,'' MSHA has not
adopted this term in the final rule, but instead has substituted the
term ``miner's designee.'' Also, because no commenter supported MSHA's
proposed definition of a ``hearing conservation program,'' that
definition has not been adopted in the final rule. In its place, MSHA
is incorporating the elements of a traditional hearing conservation
program into the text of the final rule.
Several commenters requested that MSHA provide a definition for
``feasible'' engineering and administrative controls, indicating that
the term is vague and subject to varying interpretations. Because of
the performance-oriented nature of the requirements for the use of
engineering and administrative controls, MSHA has refrained from
including an explicit definition of this term. Rather, MSHA notes in
the discussion under ``Feasibility'' (Part VI of this preamble), that
it follows the Federal Mine Safety and Health Review Commission case
law as to what constitutes a feasible noise control for enforcement
purposes. MSHA further notes in that discussion that it will provide
additional guidance in a companion compliance guide to this final rule.
A few comments were received regarding MSHA's use of non-standard
terminology and abbreviations in the proposal, in particular, the use
of the terms ``decibel A-weighted,'' ``dBA,'' and ``sound level (in
dBA).'' MSHA intends for the terminology used throughout this rule to
be both
[[Page 49578]]
technically correct and readily understood. Therefore, for technical
accuracy and consistency with usage in the mining community for the
past 25 years, the Agency is deleting the definition of the term
``decibel A-weighted'' and is rephrasing the definition of the term
``sound level.''
The following is a summary of some of the key features of the
definitions that are used in the final rule along with a discussion of
the comments that the Agency received in response to the proposal.
Access is the right to examine and copy records. MSHA is adopting
the definition from the proposal, which is consistent with the term
used in several of MSHA's and OSHA's existing health standards. In
response to commenters who requested that MSHA include a ``no cost''
provision in this definition, MSHA notes that such a provision is
included in the specific section in which it would be applicable. The
term ``access'' is discussed further under Sec. 62.190, regarding
records.
Action level is an 8-hour time-weighted average sound level
(TWA8) of 85 dBA, or equivalently a dose of 50%, integrating
all sound levels from 80 dBA to at least 130 dBA. The action level is
discussed further under Sec. 62.120 of the preamble.
Audiologist is a professional specializing in the study and
rehabilitation of hearing and who is certified by the American Speech-
Language-Hearing Association or is licensed by a state board of
examiners. The vast majority of commenters indicated no preference for
further restrictions to MSHA's proposed definition, which is identical
to that used by OSHA in its occupational noise standard.
Some commenters, however, believed that the definition of
``audiologist'' should specifically require certification by the
American Speech-Language Hearing Association (ASHA), as evidenced by a
Certificate of Clinical Competence. Other commenters supported a
proviso being added to the definition of ``audiologist'' that state
licensing requirements guarantee that the licensees are as competent as
those certified by ASHA. The rationale for this comment was that state
licensing boards vary significantly from state to state, and licensing
requirements in some states are not as stringent as ASHA certification
requirements.
The final rule does not adopt the suggestion of commenters that the
final rule accept licensing by only those states whose licensing
standards are sufficiently rigorous, because although some state
licensing requirements are more stringent than others, even the least
rigorous of the state requirements will provide an acceptable level of
competence for audiologists. The final rule adopts the requirement that
audiologists hold an ASHA certification or a license from a state board
of examiners, which is consistent with MSHA's determination that such a
certification or license is essential to the implementation of an
effective hearing conservation program. Properly trained and certified
audiologists are qualified to conduct audiometric testing, evaluate
audiograms, and supervise technicians who conduct and evaluate
audiograms.
The licensing requirements for audiologists in the final rule are
also consistent with similar requirements in OSHA's noise standard. The
term ``audiologist'' is discussed further under Sec. 62.170 of the
preamble regarding audiometric testing.
Baseline audiogram is the audiogram, recorded in accordance with
Sec. 62.170 of this part, against which subsequent audiograms are
compared to determine the extent of hearing loss, except in those
situations in which this part requires the use of a revised baseline
audiogram for such a purpose. With the exception of the term
``revised,'' which replaces the term ``supplemental,'' the definition
of baseline audiogram is unchanged from the proposal. The baseline
audiogram establishes a reference for making hearing loss
determinations.
Although many commenters favored the proposal, others believed that
a true baseline, by definition, is conducted prior to exposure to
noise. MSHA notes that the final rule explicitly allows mine operators
to use existing audiograms as the baseline, provided that they were
taken under the conditions meeting the testing requirements of this
rule. For the final rule, the Agency concludes that the reasons
discussed in the preamble to the proposal remain valid. There MSHA
discussed the importance of the testing requirements that are to be
followed in conducting the baseline audiogram, as it is the reference
against which subsequent audiograms are to be compared. If the baseline
audiogram is not conducted properly, it will not truly reflect the
miner's hearing thresholds. As a result, any changes between the
baseline and subsequent tests may be masked. Accordingly, MSHA is
adopting the proposed definition.
The definition of baseline audiogram also includes the provision
that hearing loss determinations may require the use of a ``revised''
baseline under specific circumstances. Those circumstances are noted in
the further discussion of baseline audiogram and audiometric testing
under Sec. 62.170(a) of the final rule.
Criterion level refers to the sound level which, if applied for 8
hours, results in 100% of the dose permitted by the standard. The
definition remains unchanged from the proposal. Under
Sec. 62.110(b)(2)(iv) of the final rule, the criterion level is a sound
level of 90 dBA. If applied for 8 hours, this sound level will result
in a dose of 100% of the permissible exposure level (PEL), established
by Sec. 62.130 as an 8-hour time-weighted average (TWA8) of
90 dBA. The criterion level is a constant. On the other hand, the
permissible exposure level is a sound level of 90 dBA for 8 hours or a
sound level of 95 dBA for 4 hours. Further discussion is provided under
Sec. 62.110(b)(2)(iv) of the preamble regarding dose determination.
Decibel (dB) is a unit of measure of sound pressure levels. It is
defined in the final rule in one of two ways, depending upon the use.
The proposed definition remains unchanged; it continues to include
definitions for measuring sound pressure levels and for measuring
hearing threshold levels:
(1) For measuring sound pressure levels, the decibel is 20 times
the common logarithm of the ratio of the measured sound pressure to the
standard reference sound pressure of 20 micropascals (Pa),
which is the threshold of normal hearing sensitivity at 1000 Hertz; and
(2) For measuring hearing threshold levels, the decibel is the
difference between audiometric zero (reference pressure equal to 0
hearing threshold level) and the threshold of hearing of the individual
being tested at each test frequency.
Dual Hearing Protection Level is a TWA8 of 105 dBA, or
equivalently, a dose of 800% of that permitted by the standard,
integrating all sound levels from 90 dBA to at least 140 dBA. In the
proposal, the definition was included within the dual hearing
protection requirement itself. The term is set forth as a definition in
the final rule for the sake of clarity.
Exchange rate is the amount of increase in sound level, in
decibels, which would result in reducing the allowable exposure time by
half in order to maintain the same noise dose. In response to a comment
which requested clarification of this definition, MSHA has added
language to the final rule which states that for purposes of this part,
the exchange rate is 5 decibels (5 dB). In the final rule, a 5-dB
increase or decrease in the sound level corresponds to a halving or
doubling of the allowable exposure time. Thus, a 5-dB increase, from 90
dBA to 95 dBA, would result
[[Page 49579]]
in halving the allowable exposure time from 8 hours to 4 hours, and a
5-dB decrease, from 100 dBA to 95 dBA, would result in doubling the
allowable exposure time from 2 hours to 4 hours. Exchange rate is
discussed further under Sec. 62.110(b)(2)(iv), regarding dose
determination.
Hearing protector refers to any device or material, capable of
being worn on the head or in the ear canal, sold wholly or in part on
the basis of its ability to reduce the level of sound entering the ear,
and which bears a scientifically accepted indicator of noise reduction
value. The proposed definition remains unchanged in the final rule.
Although one commenter suggested that the phrase ``sold wholly or in
part on the basis of its ability to reduce the level of sound'' be
deleted from this definition because a hearing protector's
effectiveness cannot be reliably determined on the basis of the
intended purpose for which it is sold, MSHA's definition follows the
Environmental Protection Agency's (EPA) labeling standards for hearing
protectors (40 CFR Sec. 211.203(m)). Under the EPA labeling standards,
a hearing protector is defined as:
* * * any device or material, capable of being worn on the head or
in the ear canal, that is sold wholly or in part on the basis of its
ability to reduce the level of sound entering the ear.
This includes devices of which hearing protection may not be the
primary function, but which are nonetheless sold partially as
providing hearing protection to the user.
Accordingly, MSHA is adopting the proposed definition. As a result,
not all devices or materials that are inserted in or that cover the ear
to reduce the noise exposure qualify as a hearing protector under the
final rule. For example, a hearing aid or cotton does not qualify as an
acceptable hearing protector under the final rule.
Although several commenters agreed with the proposal that the
hearing protector should be required to have a scientifically accepted
indicator of noise reduction value, other commenters suggested that
MSHA's definition specifically include the manufacturer's noise
reduction rating (NRR) or a requirement that the attenuation be
measured according to standards of the American National Standards
Institute (ANSI). Since EPA requires that all hearing protector
manufacturers include labeling information indicating a noise reduction
rating, a hearing protector bearing such a label would indicate to a
mine operator that it meets MSHA's definition of a hearing protector.
However, MSHA is not limiting the range of hearing protectors only
to those with a noise reduction rating. MSHA noted in the preamble to
the proposed rule that the noise reduction ratings do not reflect
actual reductions in noise in workplace situations. Moreover, other
organizations have recommended that the EPA reconsider its rating
system. Therefore, MSHA is adopting the language in the proposed
definition which permits any scientifically accepted indicator of noise
reduction value. Further discussion of noise reduction ratings is
located under Sec. 62.110(b)(2)(i), regarding noise exposure
assessment.
Hertz (Hz) is the international unit of frequency, equal to cycles
per second. The definition has been changed from the proposal. One
commenter suggested that stating the range of audible frequencies for
humans with normal hearing is superfluous to a definition for hertz.
MSHA agrees, and the reference has not been adopted in the final rule.
Medical pathology is a condition or disease affecting the ear. The
definition of medical pathology remains unchanged from the proposal. A
few commenters suggested that the definition be reworded. The term,
which is also used in OSHA's occupational noise standard, is adopted in
MSHA's final rule for use in contexts which do not require actual
diagnosis and treatment, but which may ultimately be diagnosed and
treated by a physician. The Agency intends that ear injuries be
included as a condition or disease affecting the ear. Medical pathology
is discussed further in the preamble sections addressing
Sec. 62.160(a)(5), regarding hearing protectors, Sec. 62.172(b)(1),
regarding evaluation of audiograms, and Sec. 62.173(a) and (b),
regarding follow-up evaluation when the audiogram is invalid.
Miner's designee is any individual or organization to whom a miner
gives written authorization to exercise the miner's right of access to
records. This definition is new to the final rule. MSHA received
several comments to the proposal's use of the term ``designated
representative,'' which caused confusion with the term ``representative
of miners'' in 30 CFR Sec. 40.1(b). MSHA intended that the two terms
have distinct meanings. Accordingly, for clarification, MSHA has
replaced the proposed term with the new term, ``miner's designee.''
Further discussion of the term ``miner's designee'' is found under
Sec. 62.190(b), regarding records.
Permissible exposure level is a TWA8 of 90 dBA or
equivalently a dose of 100% of that permitted by the standard,
integrating all sound levels from 90 dBA to at least 140 dBA. No miner
shall be exposed during any work shift to noise that exceeds the
permissible exposure level. The permissible exposure level is discussed
further under Sec. 62.130 of the preamble.
Qualified technician is a person who has been certified by the
Council for Accreditation in Occupational Hearing Conservation (CAOHC)
or by another recognized organization offering equivalent
certification. The proposed definition remains unchanged in the final
rule.
Several commenters suggested additional requirements while other
commenters favored less restrictive requirements for the qualified
technician: some commenters did not agree with the proposed requirement
that a qualified technician be certified by the Council for
Accreditation in Occupational Hearing Conservation or by another
recognized organization offering equivalent certification. Several
commenters recommended that MSHA adopt the requirements for technicians
in the OSHA noise rule, which allows physicians and audiologists
discretion to judge the qualifications of technicians. A number of
commenters advocated that the final rule be consistent with the OSHA
noise standard and exempt technicians who operate microprocessor
audiometers from any certification requirement. This was based on the
commenters' views that a properly trained technician, under the
direction of a physician or an audiologist, would have the competence
to perform the tests. These commenters believed that a requirement for
certification by CAOHC or an equivalent body would unnecessarily limit
the flexibility of mine operators in testing employees, and could
result in fewer tests being conducted. One commenter stated that the
final rule should require CAOHC certification as the minimum
qualification for audiometric technicians, and not accept
certifications by other organizations, pointing out that CAOHC is
currently the only organization that currently issues such
certifications.
MSHA has concluded that a certification requirement for audiometric
technicians is not overly restrictive, and it ensures the necessary
level of knowledge and proficiency to perform audiometric tests under
the final rule. MSHA has also concluded that certifications from
organizations other than CAOHC are acceptable, provided that the
organization imposes equivalent requirements. Contrary to the
statements of some commenters, CAOHC is not the only organization that
issues such certifications--the U.S. armed forces train technicians to
[[Page 49580]]
perform audiometric tests and issues certifications. Such
certifications would be accepted under the final rule.
The final rule also adopts the proposed requirement that
technicians who operate microprocessor audiometers have CAOHC or
equivalent certification, to ensure that these technicians demonstrate
the same level of proficiency as those technicians who operate manual
audiometers. Although microprocessor audiometers may be easier to
operate than manual audiometers, MSHA has concluded that a
certification requirement is still appropriate for technicians who
operate this equipment. MSHA's final rule, unlike OSHA's noise
standard, does not include detailed procedural requirements for
audiometric testing. Instead, the training and expertise of the
individuals conducting tests is an essential element of an effective
audiometric testing program. For these reasons, MSHA has chosen not to
exempt technicians who operate microprocessor audiometers from the
certification requirements in the final rule. Further, the requirement
for CAOHC or equivalent certification is not overly burdensome on the
mining industry, as 19,000 technicians currently hold this
qualification due to OSHA's requirement for CAOHC certification. The
19,000 CAOHC technicians are located around the country.
The requirements for audiometric technicians in the final rule are
similar to requirements in regulations of the
U.S. Army, Air Force, and Navy, which require the technician to be
CAOHC-certified or certified through equivalent military medical
training and be under the supervision of a physician or audiologist.
Qualified technicians are further discussed under Sec. 62.170,
regarding audiometric testing and Sec. 62.172(a)(2), regarding
evaluation of audiograms.
Reportable hearing loss is a change in hearing sensitivity for the
worse, relative to the miner's baseline audiogram or a revised baseline
audiogram established in accordance with Sec. 62.170(c)(2), of an
average of 25 dB or more at 2000, 3000, and 4000 Hz in either ear. The
definition of reportable hearing loss remains essentially unchanged
from the proposal, with the exception that the proposal's reference to
``supplemental baseline audiogram'' has been replaced with ``revised
baseline audiogram.''
Under the final rule, reportable hearing loss is calculated by
subtracting the current hearing levels from those on the baseline
audiogram at 2000, 3000, and 4000 Hz and may be corrected for age. When
the permanent hearing loss at all three frequencies is averaged, the
hearing loss must be reported if the average loss in either ear is 25
dB or greater. In making this calculation, a revised baseline would be
established and used where there has been a significant improvement in
hearing sensitivity, in accordance with the provisions of
Sec. 62.170(c)(2).
MSHA is adopting the proposed definition of reportable hearing
loss--the extent of hearing loss that must be reported to the Agency
pursuant to Sec. 62.175(b) of the final rule. Some commenters who were
satisfied with the proposed 25-dB level for reporting a hearing loss
expressed concern that the proposed requirement does not discriminate
between occupational and non-occupational hearing loss. Other
commenters favored a lower, 10 dB or 15 dB, hearing loss for
reportability purposes because the proposed 25-dB hearing loss level
permits too much damage to occur before reporting is required. Still
other commenters recommended that a hearing loss should be reportable
only if it is the subject of a workers' compensation award. These
commenters believed that workers' compensation data would make good
reporting criteria and also noted that the accuracy of the reported
data could be confirmed with state workers' compensation agencies.
Additionally, the complex calculations currently necessary for
determining whether a reportable hearing loss has occurred could be
avoided.
MSHA's definition of a reportable hearing loss represents a
substantial loss of hearing, which would provide a reliable indication
of the effectiveness of the intervention strategies of the mining
industry. The requirement is consistent with the existing OSHA noise
standard which requires any 25-dB loss to be recorded in an employer's
records. In addition, Sec. 62.175(b) of the final rule, which is
identical to Sec. 62.190 of the proposal, creates an exception for
reportable hearing loss when a physician or audiologist has determined
that the loss is neither work-related nor aggravated by occupational
noise exposure. Furthermore, workers' compensation reporting criteria,
which are controlled by the states and varies from state to state, may
produce inconsistent reporting to MSHA, depending upon the state
criteria that are being applied. Further discussion of reportable
hearing loss is provided under Sec. 62.175(b), regarding the
notification of audiometric test results and reporting requirements.
Revised baseline audiogram is an annual audiogram designated, as a
result of the circumstances set forth in Sec. 62.170(c)(1) or (c)(2),
to be used in lieu of the baseline audiogram in measuring changes in
hearing sensitivity. With the exception of the clarifying change in
terms from ``supplemental'' baseline audiogram to ``revised'' baseline
audiogram, the definition in the final rule remains unchanged from the
proposal. Use of the term ``revised'' is consistent with the OSHA noise
standard. Some commenters suggested using the term ``reference''
baseline audiogram, however; MSHA believes that less confusion will
result by adopting the term used by OSHA. In addition, for further
clarity and accuracy, MSHA is replacing the proposed reference to
hearing ``acuity'' with hearing ``sensitivity.'' Further discussion of
a revised baseline audiogram is provided under Sec. 62.170(c), in
addition to the related discussions on reportable hearing loss and
standard threshold shift.
Sound level is the sound pressure level in decibels, measured using
the
A-weighting network and a slow response. The final definition is
essentially unchanged from the proposal but is reworded for accuracy.
Sound consists of pressure changes in air caused by vibrations. These
pressure changes produce waves that move out from the vibrating source.
The sound level is a measure of the amplitude of these pressure changes
and is generally perceived as loudness. For the purpose of this rule,
the sound level is expressed in the unit ``dBA.''
Under Sec. 62.110(b)(2)(v) of the final rule, sound pressure levels
would be measured using the
A-weighting network and the slow response. A-weighting refers to the
frequency response network closely corresponding to the frequency
response of the human ear. This network reduces sound energy in the
upper and lower frequencies (less than 1000 and greater than 5000 Hz)
and slightly amplifies sound energy between the frequencies of 1000 and
5000 Hz. The slow-response time refers to the slow exponential-time-
averaging characteristic. The specifications of the A-weighting network
and the slow-response time are found in ANSI S1.25-1991,
``Specification for Personal Noise Dosimeters,'' and ANSI S1.4-1983,
``American National Standard Specification for Sound Level Meters.''
A few commenters were concerned that MSHA's abbreviation ``dBA''
was technically incorrect, because it is the sound level that is A-
weighted, not the decibel. MSHA recognizes that there are several
scientific fields employing distinct acoustical terminology,
[[Page 49581]]
including noise-control engineering, mining engineering and industrial
hygiene. A term that is conventional or commonly accepted in one field
may not be accepted in another. Because the abbreviation ``dBA'' has
come to be a widely accepted way of succinctly denoting a sound level
that is A-weighted and because the majority of the mining community has
used this terminology over the past 25 years and did not voice any
opposition, MSHA has adopted the proposed abbreviation ``dBA'' in the
final rule. Further discussion of the A-weighting and slow response
time are provided under Sec. 62.110(b)(v), regarding noise exposure
assessment.
Standard threshold shift is a change in hearing sensitivity for the
worse relative to a miner's baseline audiogram or relative to the most
recent revised audiogram, where one has been established. The hearing
loss is calculated by subtracting the current hearing levels from those
measured by the baseline or revised baseline audiogram at 2000, 3000,
and 4000 Hz, and, optionally, correcting for age. A standard threshold
shift is defined as when the average loss in either ear has reached 10
dB. The proposal is essentially unchanged, except that the term
``sensitivity'' has replaced the term ``acuity.''
OSHA defines a standard threshold shift in essentially the same way
and requires that an employee's annual audiogram be compared to his or
her baseline audiogram to determine if the annual audiogram is valid
and if a standard threshold shift has developed.
NIOSH (1995) recommends that the criteria for a standard threshold
shift be a 15-dB decrease in hearing sensitivity at any one of the
audiometric test frequencies from 500 to 6000 Hz on two sequential
audiograms. The shift in hearing sensitivity must be in the same ear.
NIOSH believes this criteria is sufficiently stringent to detect
developing hearing loss while excluding normal variability in workers'
hearing sensitivity. NIOSH's previous (1972) criteria defined standard
threshold shift as a change of 10 dB or more at 500, 1000, 2000 or 3000
Hz; or 15 dB or more at 4000 or 6000 Hz.
MSHA's definition of standard threshold shift in the final rule
will identify individuals suffering shifts as large as 30 dB at 4000 Hz
with no shifts at the lower frequencies. This permits the early
identification of individuals at risk, so that corrective measures may
be instituted. For example, there are some instances where significant
threshold shifts in hearing level occur at higher test frequencies
(4000 and 6000 Hz) with little or no change in hearing level at the
middle frequencies. While such large shifts are uncommon, they may
occur in noise-sensitive individuals, especially in the early stages of
noise-induced hearing loss.
Many commenters voiced concern that any hearing loss would be
considered a result of occupational noise exposure. These commenters
believed that many non-occupational causes could produce a hearing loss
and that MSHA should recognize such non-occupational origins of hearing
loss. As stated elsewhere in this preamble, MSHA leaves it to the
professional judgement of medical and technical personnel to determine,
through interviewing and thorough examination, whether the origin of
hearing loss is occupational or non-occupational.
MSHA believes, after considering the relevant factors and reviewing
current U.S. armed forces and international standards, that the
definition of a standard threshold shift in the final rule is the most
appropriate. Further discussion is provided under Sec. 62.172,
regarding the evaluation of audiograms.
Time-weighted average-8 hour (TWA8) is the sound level
which, if constant over 8 hours, would result in the noise dose
measured. The proposed definition remains unchanged in the final rule.
This value is used in the final rule in connection with various limits;
for example, the permissible exposure level is a TWA8 of 90
dBA and the action level is a TWA8 of 85 dBA.
Not all noise-measurement instruments provide readouts in terms of
an 8-hour time-weighted average. Personal noise dosimeters, for
example, measure noise as a percentage of permitted dosage, with the
permissible exposure level equated to 100%. Noise dose may be
converted, in accordance with Sec. 62.110 of the final rule, to an
equivalent TWA8 to determine if the action level or the
permissible exposure level has been exceeded and to evaluate the impact
of engineering and administrative controls. Accordingly, MSHA has
provided a list of TWA8 conversion values in Table 62-2 of
the final rule, based on a criterion level of 90 dBA for 8 hours.
Noise exposure must be determined for the entire shift, but
regardless of the length of the work shift, a determination of
noncompliance with the noise standard will be based upon exceeding 100%
exposure and the TWA8 (and a 5-dB exchange rate). It would
thus be improper to adjust a TWA8 reading for an extended
work shift.
Section 62.110 Noise Exposure Assessment
The requirements of Sec. 62.110 of the final rule have been adopted
from both the proposal and supplemental proposal to include in one
section all provisions that address mine operators' assessment and
evaluation of miners' noise exposures. The provisions of this section
of the final rule include the requirements that mine operators:
(1) Establish a system to monitor miners' noise exposures;
(2) Evaluate each miner's noise exposure to determine continuing
compliance with this part;
(3) Provide affected miners and their representatives the
opportunity to observe noise exposure monitoring; and
(4) Notify miners when their noise exposure equals or exceeds
certain limits set by this final rule.
The provisions of this section are similar to provisions in
Sec. 62.120(a) and (f) of the proposal and Sec. 62.120(g) of the
supplemental proposal. The final rule, like the proposal, requires the
mine operator to establish a system of monitoring to evaluate each
miner's noise exposure. The monitoring requirement establishes specific
goals for a mine operator's monitoring system, including:
(1) Determining if miners' noise exposures reach any of the limits
established by this final rule;
(2) Assessing the effectiveness of the engineering and
administrative noise controls in place;
(3) Identifying areas of the mine where the use of hearing
protectors is required; and
(4) Ensuring that the noise exposure information necessary for
proper evaluation of miners' audiograms is furnished to audiometric
test providers.
The rule is flexible, that is, it does not prescribe how the mine
operator will accomplish the goals it sets, but rather leaves it to the
mine operator to determine the best means by which to achieve those
goals.
Like the supplemental proposal, the final rule requires the mine
operator to give prior notice to affected miners and their
representatives of the date and time of exposure monitoring by the mine
operator, and to provide miners and their representatives the
opportunity to observe such monitoring.
The final rule also requires that the mine operator notify miners
in a timely manner if their noise exposures reach the levels specified.
This ensures that miners are aware that they have been exposed to
excessive noise and may encourage them to use the hearing protectors
provided by the mine
[[Page 49582]]
operator and participate in the audiometric testing program provided by
the mine operator. Miners must also be notified of the corrective
action taken if their exposures exceed the permissible exposure level.
System of Monitoring
Paragraph (a) of Sec. 62.110 of the final rule requires mine
operators to establish a system of monitoring that evaluates each
miner's noise exposure sufficiently to determine continuing compliance
with all aspects of the final rule. The final rule, like the proposal,
takes a performance-oriented approach, and neither the methodology nor
the intervals of monitoring are specified. Under Sec. 62.120(f) of the
proposed rule, mine operators would have been required to establish a
system of monitoring ``which effectively evaluates each miner's noise
exposure.''
Despite a number of commenters who questioned the need for
monitoring by the mine operator, MSHA has determined that operator
monitoring is needed to identify those miners who are subjected to
noise exposures that may be injurious to their hearing, so that
protective measures can be implemented. Most commenters supported the
need for monitoring and favored a performance-oriented approach, but
some suggested a detailed specification-oriented monitoring program
similar to the program previously applicable to coal mines. Those
commenters questioned how MSHA would evaluate ``an effective system of
monitoring,'' urging MSHA to define this term. Other commenters
questioned mine operators' ability to conduct reliable noise exposure
monitoring.
MSHA intends to evaluate the effectiveness of mine operators'
monitoring programs by how well the programs achieve the specified
goals. During mine inspections, MSHA will continue to evaluate miners'
noise exposures. Overexposures may indicate deficiencies in the mine
operator's noise monitoring program, and may result in close scrutiny
of the program by MSHA. In view of the wide variety of mining
operations to which the final rule applies, MSHA has concluded that the
establishment of rigid and specific monitoring requirements would be
unnecessarily inflexible and stifle innovation and improvements in
monitoring technology. The test of whether the monitoring system is
effective is how well the monitoring system protects miners. Thus, a
monitoring program which meets the specified goals will be considered
effective under the final rule.
Another concern of commenters was the proposed requirement that
mine operators establish a system of monitoring which ``effectively
evaluates each miner's noise exposure.'' These commenters expressed
concern that this provision could place an undue burden on mine
operators. Many of these commenters suggested that monitoring areas of
the mine, representative job tasks, or similar occupations would be
sufficient to meet the intent of the rule. A few commenters suggested
that monitoring should occur only when information exists that a
miner's noise exposure equals or exceeds the action level. According to
one commenter, because a mine operator's insurance carrier may conduct
noise exposure monitoring, monitoring by the mine operator would not be
necessary.
In response to these commenters, the language of this section of
the final rule has been reworded to provide that the mine operator must
establish a system of monitoring that ``evaluates each miner's noise
exposure sufficiently to determine continuing compliance with this
part.'' This reflects the intent of both the proposal and the final
rule, and does not require that each miner be individually evaluated
for noise exposure, provided that the established monitoring system
serves to detect individual miner exposures equaling or exceeding the
specified levels in the final rule. As noted by commenters, depending
upon the circumstances, monitoring of areas of the mine or
representative job tasks may provide a mine operator with sufficient
information to determine compliance with the final rule. Regardless of
the system of monitoring that a mine operator implements, mine
operators continue to be fully responsible for ensuring that no miner
is exposed to noise above permissible limits, and for ensuring that the
required corrective actions are taken if a miner's noise exposure
equals or exceeds the action level or exceeds the permissible exposure
level or the dual hearing protection level. As indicated in the
preamble to the proposed rule, a mine operator could use results of
MSHA sampling or information from equipment manufacturers on the sound
levels produced by their equipment in determining compliance with this
rule. Additionally, as suggested by one commenter, a mine operator
could also consider the results of other sampling, such as sampling
conducted by an insurance carrier, in determining compliance. It would
nonetheless benefit mine operators to determine miners' noise exposure
using a personal noise dosimeter or the formula included in paragraph
(b) of this section of the final rule.
Determination of Dose
Paragraphs (b)(1) and (b)(2) of Sec. 62.110 of the final rule
include requirements for determining a miner's noise dose. These
requirements are essentially the same as those in Sec. 62.120(a) of the
proposal. They contain several revisions in language to accommodate the
changes in the threshold and range of integration for the permissible
exposure level and dual hearing protection level. Additionally, the
final rule, unlike the proposal, specifically refers to the use of
personal noise dosimeters in determining a miner's noise dose. Finally,
the final rule does not adopt the term ``miner's noise exposure
measurement'' used in the proposal, but instead substitutes the term
``miner's noise dose determination'' to be consistent with the flexible
and performance-oriented approach taken by the final rule. This change
in terminology reflects the fact that mine operators may choose to
determine a miner's noise dose and comply with the requirements of the
final rule without taking an actual, physical measurement of a miner's
personal noise exposure.
Paragraph (b)(1) of Sec. 62.110 provides that a miner's noise dose
may be determined in one of two ways:
(1) Through the use of a personal noise dosimeter; or
(2) When sound levels and corresponding exposure times are known,
the dose is computed using the specified formula.
In order to use the formula, it is necessary to know the distribution
of sound levels and exposure times throughout the work shift. Table 62-
1 provides reference durations for the sound levels to be used in the
calculation of dose, and Table 62-2 addresses converting from dose
readings to equivalent TWA8 values.
The ratios of the actual exposure times to the reference duration
for each specified sound level equal to or exceeding the threshold
(lower bound on the integration range) are summed and expressed as a
percentage of the permitted standard. A reference duration is the time
over which a miner, exposed at the associated sound level, receives
100% of the permissible noise dose. The reference duration for an 80-
dBA sound level was added to the table in the final rule to reflect the
use of the 80-dBA threshold for the determination of conformance with
the action level, and is consistent with OSHA's noise standard.
[[Page 49583]]
Formula for Computing a Miner's Noise Exposure
If a sound level meter is used, corresponding discrete exposure
times for each sound level are determined, and the formula established
in this section is used to compute the miner's noise exposure. A
personal noise dosimeter automatically computes a miner's noise
exposure in the same manner as the formula does for readings taken with
a sound level meter over the entire measurement period.
Like the proposal, the final rule includes Table 62-1, which lists
incremental sound levels and their associated reference durations. The
table in the final rule differs from the table included in the proposal
because the sound levels that must be integrated into the noise
exposure determination under the final rule are different than they
would have been under the proposal for the permissible exposure level
and the dual hearing protection level (see Secs. 62.120, 62.130, and
62.140). These sound levels are essentially the same as those shown in
Table G-16a in the OSHA noise standard, except that values above 115
dBA are excluded.
Although sound levels in excess of 115 dBA are not shown in Table
62-1, they are to be integrated into the noise exposure determination.
However, inclusion of these values in Table 62-1 might lead the reader
to erroneously infer that a miner is permitted to be exposed to sound
at such levels, contrary to Sec. 62.130(c) of the final rule, which
prohibits the exposure of miners to sound levels exceeding 115 dBA. To
avoid any such confusion, Table 62-1 has not been expanded to include
the corresponding reference durations for sound levels greater than 115
dBA. Additionally, the Table includes the notation that at no time must
any excursion exceed 115 dBA. MSHA notes that, in any case, the
reference durations for sound levels that are not in the table can be
calculated in accordance with the formula in the table's note. Further,
discussion of the range of sound levels that are integrated into a
miner's noise dose is included under Sec. 62.110(b)(2), regarding range
of integration.
Conversion From Dose to TWA8
Table 62-2 is provided to allow conversion of the dose (percent) to
the equivalent eight-hour time-weighted average (TWA8). The
requirements of paragraph (b)(1) have been adopted unchanged from
Sec. 62.120(a)(2) of the proposal. However, the full shift over which
the dose determination is made may be shorter or longer than 8 hours.
Thus, the table is included because it provides an easy reference for
converting the noise dose expressed as a percentage of the permissible
exposures to the corresponding TWA8.
MSHA noted in the preamble to the proposed rule that the
TWA8 and the dose are to be used interchangeably, and that
the TWA8 is not to be adjusted for extended work shifts,
because the criterion level is based on eight hours. Noise exposures
must reflect the entire shift in order to determine compliance with the
final rule. If the noise dose exceeds 100 percent, regardless of the
length of the work shift, the miner will be considered to be
overexposed to noise. MSHA requested that commenters provide
suggestions to help the Agency ensure that its intent is clearly
conveyed in this final rule, but received no additional comments. The
Agency provides the following additional guidance. If a miner's noise
dose exceeds 800 percent, regardless of the length of the work shift,
the miner will be considered to be exposed above the dual hearing
protection level. If a miner's noise dose equals or exceeds a
TWA8 of 85 dBA, regardless of the length of the work shift,
the miner will be considered to be exposed above the action level.
Since the action level and permissible exposure level are determined
using 80-dBA and 90-dBA thresholds, respectively, the noise dose using
the 90-dBA threshold will always be lower or equal to the noise dose
using the 80-dBA threshold.
Table 62-2 has been constructed by equating the permissible
exposure level to a dose of 100 percent (criterion level of a
TWA8 of 90 dBA). More specifically, the TWA8
conversion values in Table 62-2 are based on the use of a 90-dBA
criterion level and a 5-dB exchange rate. Interpolation for values not
found in this table can be determined using the following formula:
TWA8 = 16.61 log10 (D/100) + 90, where D is
the dose. Table 62-2 can be used to determine the equivalent
TWA8 from the percent noise dose. The conversion is made
from dose in percent to TWA8, regardless of the work shift
time, and compared to the action level (TWA8 of 85 dBA), the
permissible exposure level (TWA8 of 90 dBA), or dual hearing
protection level (TWA8 of 105 dBA). Some models of personal
noise dosimeters will provide readings in both the percent dose and
TWA8, and in such cases the conversion table would not be
needed.
MSHA notes here, as it did in the preamble to the proposal, that
noise exposure is interpreted as if averaged over 8 hours. For example,
a dose of 200 percent is equivalent to a TWA8 of 95 dBA,
whether it is collected for 4 hours, 8 hours, or 12 hours, and would
indicate noncompliance with the permissible exposure level. A miner
working only 5 or 6 hours can be exposed to higher sound levels during
those hours than during an 8-hour shift. Thus, although exposure at 95
dBA is not permitted for 8 hours, exposure at that level would be
permitted for a 4-hour work shift. Conversely, if a miner works a shift
longer than 8 hours, the sound levels would need to be lower. Thus,
although exposure at 90 dBA is permitted for 8 hours, it is not
permitted for a 10-hour work shift. In this way, the conversion of
percent dose to TWA8 simplifies compliance determination.
Paragraph (b)(2) of this section (1) prohibits adjustments of dose
determinations for the use of hearing protectors; (2) specifies the
minimum range of sound levels that must be included in a miner's noise
dose determination; (3) requires that the dose determination reflect
the miner's full shift; (4) requires the use of a 90-dB criterion level
and a 5-dB exchange rate; and (5) requires the use of an A-weighting
and slow response instrument setting.
Noise Reduction Ratings
Section 62.110(b)(2)(i) of the final rule remains unchanged from
Sec. 62.120(a)(3)(i) of the proposal and requires that a miner's noise
exposure be determined without adjusting for the use of any hearing
protector. MSHA chose not to require the use of any method to determine
the effectiveness of hearing protectors. Similarly, the Agency also
chose not to provide for any scheme for the use or derating of the
noise reduction rating (NRR) currently determined by manufacturers for
hearing protectors based on laboratory testing under Environmental
Protection Agency (EPA) regulations at 40 CFR Secs. 211.201 through
211.214. The noise reduction rating is an estimate of the noise
reduction achievable under optimal conditions and was designed to be
used with C-weighted sound levels. EPA regulations require every
hearing protector manufactured for distribution in the United States to
bear a label that includes the protector's noise reduction rating.
Several commenters supported this aspect of the proposal, and
agreed that the noise reduction provided by a hearing protector worn by
a miner should not be considered in determining the miner's noise
exposure. They believed the noise should be controlled by using
engineering methods, rather than by relying on
[[Page 49584]]
miners to wear hearing protectors. These commenters observed that under
MSHA's existing enforcement policy for coal mining, in many cases, once
adjustment is made for hearing protector use when determining
compliance, previously installed engineering noise controls are not
maintained. Other commenters stated that the EPA noise reduction rating
is a poor predictor of field performance; still others were of the
opinion that the noise reduction of hearing protectors should be
determined for individual wearers, not using average values such as the
EPA noise reduction ratings.
On the other hand, many other commenters believed that some
consideration of the noise reduction value of a hearing protector is
called for in determining noncompliance. Some of these commenters
stated that the EPA noise reduction rating is a scientifically accepted
indicator of noise reduction value and should be retained. A number of
those commenters believed that hearing protectors could be used
effectively and were the most cost-effective method to achieve
compliance with the rule. Other commenters recommended that hearing
protectors be rated using methods recommended by the National Hearing
Conservation Association, while others stated that the NIOSH method of
adjusting hearing protector ratings should be used. Both of these
methods are discussed below.
Several commenters provided audiometric data from their hearing
conservation programs, claiming that the data showed that hearing
protectors adequately protect the hearing sensitivity of miners. As
discussed earlier, the NIOSH (Franks) analysis of the two databases
cited by MSHA and the three analyses conducted by Clark and Bohl under
the auspices of the National Mining Association indicate that miners
are developing hearing loss of a degree that constitutes material
impairment. The differences in the conclusions of these studies are
largely attributable to different attributes of the control groups,
i.e. prior noise exposure or the existence of otological abnormalities
(which generally results in poor hearing), which were used in the
studies. As noted earlier in the preamble, Franks' analysis used a non-
noise exposed population and the audiograms of miners who had
experienced otological abnormalities were screened out. Clark and Bohl,
however, used a population that could have had an occupational noise
exposure or an otological abnormality. Because of the different
baselines, the conclusions reached by Clark and Bohl are different from
those reached by Franks regarding the magnitude of the hearing losses
exhibited by miners. In any event, although the analyses arrive at
different conclusions, all of these analyses indicate that some miners
are developing varying degrees of a material impairment of hearing.
Additionally, these analyses do not support the conclusion that a
hearing conservation program that relies primarily or exclusively on
the use of hearing protectors effectively protects all miners from
noise-induced occupational hearing loss. The Agency also notes that it
has examined data submitted by mine operators in accordance with the
Agency's notification regulations under 30 CFR Part 50. This data shows
that a number of miners have incurred a hearing loss despite the use of
hearing protectors.
Other studies and data were submitted by TU Services, Rochester
Group, Kerr-McGee Coal Corporation, and BHP Minerals Inc., in support
of their position that a hearing conservation program that relies
primarily or solely on the use of hearing protectors can adequately
protect miners' hearing. However, all these studies lack sufficient
data to allow such a conclusion to be drawn because no information has
been provided that indicates the miners' history of noise exposure; the
history of the use of hearing protectors; the type of hearing
protectors used or the circumstances of use; and what type, if any, of
engineering or administrative controls that may have been implemented.
In addition, the data or studies lacked information on employment
history and training history. Also, no details of the audiometric
testing procedures were provided to the Agency. One study submitted by
Kerr-McGee used an internal control to which the hearing of miners were
compared. However, the noise exposure of the control group was not
indicated. Because of the lack of such essential information for all
the raw data or studies submitted to the Agency, it is impossible for
MSHA to determine with any degree of certainty the level of
effectiveness of any hearing protectors that may have been used, and as
a result to give any of these studies significant weight in the
development of the final rule. Moreover data by BHP and the Rochester
Group showed the rates for a standard threshold shift (STS) to be
unacceptably high, in excess of 5% (BHP had a 7% rate and the Rochester
Group had a 6.6% STS rate in 1996 and a 7.9% STS rate between 1988 and
1997).
Some commenters recommended a requirement for NIOSH Method No. 1,
which uses the spectrum of the noise and the attenuation of the hearing
protector at individual frequencies to estimate the sound level beneath
the hearing protector. Other commenters stated their belief that mine
operators lack the sophistication to use this method. The NIOSH Method
No. 1 requires the use of advanced instrumentation and MSHA believes
that few mine operators would have the expensive instruments. In
addition, because noise in mining is almost constantly changing its
frequency, content, or sound level, many measurements of individual
noises will need to be conducted before an appropriate hearing
protector could be recommended.
In its Compendium of Hearing Protection Devices (1994), NIOSH
compares several sets of laboratory-measured noise reduction values
(obtained using various standardized methods), including the noise
reduction rating. NIOSH lists the noise reduction of various hearing
protectors estimated by these various methods. Also, listed are the
physical attributes, composition, and compatibility with other personal
safety equipment of the hearing protectors.
NIOSH (1995) recommends a rating adjustment scheme based on the
type of hearing protector, resulting in the following field-adjusted
ratings:
(1) Earmuffs--75% of the noise reduction rating;
(2) Formable earplugs--50% of the noise reduction rating; and
(3) All other earplugs--30% of the noise reduction rating.
The National Hearing Conservation Association's Task Force on
Hearing Protector Effectiveness (Royster, 1995) recommends that the
EPA's noise reduction rating be replaced with a noise reduction rating-
subject fit, or NRR(SF). According to the researchers, the NRR(SF) more
realistically reflects the field performance of hearing protectors. The
noise reduction rating-subject fit is determined by laboratory testing
after a person fits the hearing protector to his or her head. This
differs from EPA's noise reduction rating, which is determined after a
researcher fits the hearing protector to the person. Both are averages
for general populations, but the noise reduction rating-subject fit is
more realistic because it more closely approximates field conditions by
having the user insert or put on the hearing protection device. The
Task Force also recommends continued audiometric testing whenever
hearing protectors are used.
MSHA notes that the American Industrial Hygiene Association (AIHA,
[[Page 49585]]
1995) requested that EPA revise its noise rule on noise labeling
requirements for hearing protectors. The reasons given for this request
included:
(1) The current method of rating hearing protectors overestimates
the actual workplace protection by 140 to almost 2000 percent.
(2) Absolute levels of protection from labeled values cannot be
predicted.
(3) The labeled values are a poor predictor of relative performance
of one hearing protector versus another.
(4) There are no provisions for retesting the hearing protectors on
a recurring basis.
(5) There is no requirement for quality assessment or accreditation
of the test laboratory.
Despite the fact that OSHA's noise standard includes methods to
estimate the effectiveness of hearing protectors, MSHA has concluded
that there is no scientific consensus regarding the method that should
be used to determine the noise reduction of a hearing protector.
Many field studies have been conducted on the effectiveness of
hearing protectors in the mining industry. With one exception, these
studies report that hearing protectors, whether old or new, provide
much less noise reduction than was measured in the laboratory. In many
instances, noise reduction was minimal and highly variable, indicating
that hearing protector effectiveness cannot be reliably predicted under
actual use conditions and is substantially less than that indicated by
the noise reduction rating of the manufacturer. These studies are
summarized below.
Durkt (1993) studied the effectiveness of 11 models of new earmuffs
using miniature microphones inside and outside the ear cups. A total of
107 tests were conducted at surface mines on operators of equipment
that included bulldozers, front-end-loaders, and overburden drills.
When the noise spectrum included significant amounts of low frequency
noise, the measured noise reduction was much less than the noise
reduction rating. This is relevant in mining because most diesel-
powered equipment, including the machines used at the surface mines,
generate noise primarily in the low frequency range.
Kogut and Goff (1994) studied the effectiveness of earmuffs being
used in surface and underground mines. A total of 540 miners were
tested wearing their normal earmuffs. The procedure was similar, but
not identical, to the procedure used by Durkt (1993). Like Durkt, the
researchers concluded the noise reduction provided by earmuffs was
related to the spectrum of the noise. According to the researchers,
``The earmuffs' effectiveness in reducing noise exhibited great
variability and frequently fell far short of the NRR.'' The researchers
did develop a method for predicting the effectiveness of earmuffs, but
it is complex as well as impractical.
Giardino and Durkt (1996) and Giardino and Durkt (1994) expanded on
the two previously discussed studies. A total of 1,265 tests were
performed on 545 distinct machines of 20 different types. According to
the researchers, earmuffs provided minimal noise reduction for
operators of equipment powered by internal combustion engines. They
concluded that the noise reduction rating was a poor predictor of
earmuff performance under actual mining conditions.
Bertrand and Zeiden (1993), the exception noted above, determined
the effectiveness of hearing protectors by measuring the hearing levels
of miners exposed to sound levels exceeding 115 dBA. They found that,
although the hearing protectors provided less noise reduction than
their ratings indicated, the difference was not significant. For
example, miners exposed to 118 dBA experienced hearing levels
consistent with exposure to 98 dBA, indicating that the hearing
protector rated at 24 dBA provided 20 dBA of noise reduction.
Several research studies performed in other industries by Pfeiffer
(1992), Hempstock and Hill (1990), Green et al. (1989), Behar (1985),
Lempert and Edwards (1983), Crawford and Nozza (1981), and Regan (1975)
also indicate that hearing protector effectiveness is substantially
less than the noise reduction rating indicated by the manufacturer.
Other findings by these researchers sometimes conflict with one or
more of the others, underscoring the logic of MSHA's decision not to
mandate any rating adjustment system at this time:
Regan (1975) found that earmuff-type protectors provide the most
noise reduction and custom molded earplugs the least.
Behar (1985) found that the measured noise reduction rating in
industrial settings averaged 14.9 dB lower and reached 25 dB lower than
the manufacturer's rated value.
Green et al. (1989) report workers who used earplugs and were
receiving one-third to one-half of the laboratory-based noise reduction
rating value, and workers enrolled in an effective hearing conservation
program obtain greater noise reduction from their hearing protectors.
Crawford and Nozza (1981) report that the average noise reduction
of the earplugs was typically 50% of the manufacturer's values, except
for user-molded earplugs, whose actual noise reduction in the field was
near the laboratory values.
Lempert and Edwards (1983) report that, in the majority of cases,
workers received less than one-half of the potential noise reduction of
earplugs. They conclude that regardless of the type of earplug used at
a facility, a large portion of the workers obtained little or no noise
reduction.
Hempstock and Hill (1990) report that the workplace performance of
earmuffs more closely approximated the laboratory performance than
earplugs. For both earmuffs and earplugs, the measured workplace noise
reductions were lower and the standard deviations higher than those
measured in the laboratory. The researchers attribute these results to
the ease of fitting an earmuff compared to fitting an earplug. Their
study also revealed that the decrease in effectiveness was dependent
upon the model of hearing protector and even differed between sites;
safety glasses substantially degraded the performance of earmuffs;
workers wearing safety glasses received approximately one-half of the
laboratory noise reduction.
Royster et al. (1996) also found that personal protective equipment
such as hard hats and safety glasses worn by miners may affect the
noise reduction of hearing protectors. In their study, wearing safety
glasses reduced the noise reduction of earmuffs by about 5 dB at all
frequencies.
Pfeiffer (1992) surveyed studies of hearing protector effectiveness
in German industry, and reports that at industrial sites, earplugs
provided between 10 and 15 dB less noise reduction, and earmuffs about
6 dB less, than they did in the laboratory. In another part of the
study, used but not defective earmuffs were tested against new ones.
The used earmuffs provided significantly less noise reduction than new
ones. The decrease in reduction depended on the model and frequency
tested, exceeding 7 dB for some frequencies.
Abel and Rokas (1986) report that the noise reduction of earplugs
decreases with wearing time, and that head and jaw movement accelerate
the decline. Cluff (1989) investigated the effect of jaw movement on
the noise reduction provided by earplugs and determined that the change
in reduction depended on the type of earplug. Self-expanding viscose
foam earplugs retained more of
[[Page 49586]]
their noise reduction ability than multi-flanged or glass-fiber
earplugs.
At Noise-Con 81, Berger (1981) concluded that the performance of
hearing protectors decreased with wearing time. Kasden and D'Aniello
(1976, 1978) found that custom molded earplugs retained their noise
reduction after three hours of use during normal activity, but typical
earplug performance decreased after three hours of use. Krutt and Mazor
(1980) report that the noise reduction of mineral down earplugs
decreases over a three-hour period of wear, but the noise reduction of
expandable foam earplugs does not. Casali and Grenell (1989) tested the
effect of activity on the noise reduction provided by an earmuff and
found that there was significant decrease only at 125 Hz and that the
noise reduction was highly dependent on the fit.
Royster and Royster (1990) report that the noise reduction rating
cannot be used to determine or even rank the field effectiveness of
hearing protectors. They found that two individuals, using the same
model of hearing protector, can obtain vastly different levels of noise
reduction. They conclude that ``Products that are more goof-proof
(earmuffs and foam earplugs) provided higher real-world attenuation
than other HPDs [hearing protection devices].''
Casali and Park (1992) report that the noise reduction at 500 or
1000 Hz showed a high correlation with the overall noise reduction of
hearing protectors. Therefore, they believe, models can be developed to
predict the overall reduction of hearing protectors based upon the
measured reduction at a single frequency, eliminating the need to
adjust the noise reduction rating to accurately reflect noise reduction
in the field. Casali and Park also believe that this model could be
used to fit hearing protectors objectively.
Berger (1992), in ``Field Effectiveness and Physical
Characteristics of Hearing Protectors,'' reports on the progress of the
American National Standards Institute (ANSI) Working Group S12/WG11,
which is charged with developing a laboratory methodology of rating
hearing protectors that reflects the noise reduction obtained by
workers in the field. Berger also summarizes the results of 16 studies
involving over 2,600 subjects on the field performance of hearing
protectors. Earplug field ratings averaged about 25% of the published
U.S. laboratory ratings (ranging from 6% to 52%) and earmuff reduction
rates averaged about 60% of the laboratory rates (ranging from 33% to
74%).
Royster et al. (1996) also report on the progress of the American
National Standards Institute Working Group that has developed a
methodology that reflects the reduction achieved by workers in a well
managed hearing conservation program, and is in the process of drafting
an ANSI standard around it. While testing their methodology, the
researchers concluded that because some test subjects could not
properly insert an earplug by simply reading the manufacturer's
instructions, these instructions may be inadequate.
As summarized above, many researchers have compared the results of
standardized methods of measuring the noise reduction of hearing
protectors in a laboratory setting to estimated or measured field
reductions. Researchers have yet to develop a standardized test for
measuring the noise reduction of hearing protectors in the field. In
general, commenters concurred with MSHA's preliminary conclusion in the
proposal that, while methods exist to measure the noise reduction
provided to an individual by a hearing protector, none of these methods
has been standardized or shown to be effective in field usage or
applies equally to all types of hearing protectors. This makes it
virtually impossible to accurately predict in any systematic way the
in-mine effectiveness of hearing protectors in reducing noise exposures
for individual miners.
In addition to the studies that have been summarized above, MSHA
has reviewed the procedures for exposure measurement in regulations and
codes of practice (mandatory or recommended) of OSHA, selected branches
of the U. S. armed services, international communities, the
International Standards Organization, American National Standards
Institute, and the American Conference of Governmental Industrial
Hygienists. A variety of methods are used by these organizations, but
nearly all of the entities either specify or imply that noise reduction
provided by hearing protectors should not be considered in determining
a worker's noise exposure.
Accordingly, based on the rulemaking record, and consistent with
OSHA's noise standard, the final rule adopts the proposed requirement
that a miner's noise dose be measured or computed without regard to any
noise reduction provided by the use of personal hearing protectors.
This is consistent with MSHA's determination that there are other
factors that may be as important or even more important than a hearing
protector's noise reduction in ensuring that a miner is protected from
occupational noise-induced hearing loss. These factors include comfort,
training, fit, maintenance, and consistent use. Because engineering and
administrative controls are more reliable and measurable, they must be
the first line of defense in reducing noise exposures. This fact does
not, however, diminish the usefulness of hearing protectors as part of
a continuing and effective hearing conservation program. In recognition
of the role played by hearing protectors in a hearing conservation
program, MSHA will provide guidance to the mining community in
estimating the adequacy of hearing protectors as applied to individuals
in the form of a compliance guide that will be issued after the
publication of the final rule.
Range of Integration
Section 62.110(b)(2)(ii) of the final rule requires the integration
of all sound levels over the appropriate range in determining a miner's
noise dose. Under the proposal, the range of integration for the action
level, the permissible exposure level, and the dual hearing protection
level would have been from 80 to 130 dBA. The ``range of integration''
means the level at which the dosimeter starts recognizing the sound
level and counting it to the sound level where the dosimeter stops
counting. Unlike the proposal, the final rule establishes dual
thresholds: Sec. 62.120 of the final rule sets the range of integration
for the action level from 80 to at least 130 dBA, while the range of
integration for both the permissible exposure level and the dual
hearing protection level is from 90 to at least 140 dBA
(Secs. 62.130(a) and 62.140). To accommodate the dual thresholds, the
language of the final rule has been revised to require the
``appropriate range'' of integration of sound levels, rather than
specifying the range of integration set forth in the proposed rule for
all dose determinations.
The term ``all sound levels'' in the final rule includes, but is
not limited to, continuous, intermittent, fluctuating, impulse, and
impact noises. A discussion of impulse and impact noise is provided at
the end of this section.
Dual Thresholds
Many commenters urged MSHA to develop a rule consistent with the
OSHA noise standard, which requires an 80-dBA threshold for the action
level and a 90-dBA threshold for the permissible exposure level. Some
commenters, however, supported the proposed 80-dBA threshold for both
the action level and permissible exposure level. Also, a few commenters
requested that MSHA adopt a threshold of 85 dBA
[[Page 49587]]
for the permissible exposure level, while other commenters recommended
that MSHA retain the 90-dBA threshold used under MSHA's existing noise
standards, believing that sound levels less than 90 dBA were not
hazardous and that an 80-dBA threshold for compliance with the
permissible exposure level would merely increase the number of
citations without significantly benefitting the miners.
MSHA has concluded that the adoption of a dual threshold in the
final rule is protective and will decrease a miner's risk of developing
noise-induced hearing loss. In not adopting the proposed 80-dBA
threshold for both the permissible exposure level and the action level,
MSHA is not ignoring the scientific evidence, noted in Part V, Material
Impairment, which demonstrates that there is a risk of hearing loss
from exposure to sound levels at or above 80 dBA. The Agency addressed
the risk of hearing impairment from prolonged exposure above 80 dBA in
the preamble to the proposed rule. However, MSHA concludes that the
dual thresholds in the final rule will protect miners against noise-
induced hearing loss which occurs at those sound levels, primarily
because the final rule incorporates significant changes to the proposed
hearing conservation program.
MSHA has concluded that the protection provided by the final rule
adequately addresses the risk of noise-induced hearing loss which
occurs at exposures between a TWA8 of 85 dBA and a
TWA8 of 90 dBA. Under the final rule, mine operators are
required to implement a system of monitoring that evaluates each
miner's noise exposure sufficiently to determine compliance with part
62. All sound levels ranging from 80 to at least 130 dBA must be
integrated to determine whether a miner's noise exposure equals or
exceeds a TWA8 of 85 dBA--the action level. Mine operators
are required to enroll miners whose noise exposure equals or exceeds
the action level into a hearing conservation program. Under the hearing
conservation program, mine operators are required to provide enrolled
miners with hearing protectors, audiometric testing, and training, all
in accordance with specific requirements.
Commenters noted that, in addition to being protective, a dual
threshold is workable. Many mine operators are currently using personal
noise dosimeters with dual threshold capability for measuring noise
exposures. Some commenters, familiar with both OSHA and MSHA
regulations, recommend thatMSHA require measuring a worker's noise
exposure using dual thresholds in order to be consistent with OSHA.
Nearly all personal noise dosimeters currently being manufactured have
variable threshold settings that facilitate the collection of noise
exposures using two different thresholds. Some older personal noise
dosimeters that lack the capability of dual thresholds but which have
been used to measure a miner's noise exposure under MSHA's existing
noise regulations--may be somewhat obsolete, but can still be used to
make a noise exposure measurement to determine conformance with either
the action level or the permissible exposure level. They simply cannot
do both simultaneously. Additionally, some of the older instruments may
not be capable of integrating the required range of sound under the
final rule, and will need to be replaced.
Impulse/Impact Noise
As noted above, Sec. 62.110(b)(2)(ii) of the final rule requires
that ``all sound levels,'' including impulse and impact noise, be
integrated into a miner's noise dose determination. Impulse noise
sources, such as gunshots, or impact noise sources, such as a sledge
hammer striking metal, result in high sound pressure levels being
generated almost instantaneously. These sources are hazardous because
their duration is so short that the protective mechanisms of the ear do
not have sufficient time to react. The final rule, like the proposal,
does not include a separate provision for impulse or impact noise.
In the preamble to the proposed rule, MSHA discussed in depth the
many factors it considered in determining the merit of proposing an
impulse/impact noise limit for the mining industry. Although there is
evidence in the literature on the harmful effects of impulse/impact
noise, MSHA concluded that, currently, there is insufficient scientific
consensus to support a separate impulse/impact noise standard. Further,
existing procedures for identifying and measuring such sounds lack the
practicality to enable its effective measurement. This is due, in part,
to the complexity of the phenomena, where consideration must be given
to such technical factors as the peak sound pressure level, the shape
of the wave form, the number of impulses per day, the presence or
absence of steady-state (background) sound, the frequency spectrum of
the sound, and the protective effect of the middle ear acoustic reflex.
As discussed in Part V, Material Impairment, when impulse/impact
noise is combined with continuous noise, hearing loss is exacerbated.
Because industrial impulse noises are almost always superimposed on a
background of moderate-to-high levels of continuous noise, and because
both can be harmful, it is reasonable to consider their combined
effect, rather than to treat each separately. MSHA has therefore
concluded, and the final rule reflects, that impulse/impact noise must
be combined with continuous noise when a miner's noise exposure is
determined. This is consistent with provisions in OSHA's noise
standard.
MSHA has received comments on whether impulse and impact noise can
be accurately integrated into determining a miner's noise dose. The
studies cited by these commenters pre-dated the new ANSI S1.25-1991
``American National Standard Specification for Personal Noise
Dosimeters.'' Personal noise dosimeters meeting this standard cover the
ranges of sound levels that are to be integrated into a miner's noise
dose under Secs. 62.120, 62.130(a), and 62.140 and accurately integrate
impulse and impact noise into a worker's noise exposure.
MSHA received comments in response to its request for data
addressing a critical level to prevent a traumatic hearing loss. A
critical level is one which causes immediate and irreparable damage to
the hearing mechanism. The comments received dealt primarily with
impulse and impact noise as it pertained to the proposed ceiling level
of 115 dBA, and these comments are therefore addressed under
Sec. 62.130 of this preamble.
Full Work Shift
Section 62.110(b)(2)(iii) of the final rule has been adopted with
some changes from proposed Sec. 62.120(a)(3)(ii), and requires that a
miner's noise dose determination reflect the miner's full work shift.
Under the proposed rule, a miner's noise exposure measurement would
have been required to integrate all sound levels from 80 dBA to 130 dBA
during the miner's full work shift. Many commenters supported the
proposal, based on their belief that a miner's noise exposure should be
monitored for the entire work shift. Several commenters specifically
recommended that full-shift sampling also include extended work shifts,
that is, those that are longer than 8 hours. Another supported the use
of dosimetry to determine a miner's noise exposure.
MSHA received several comments suggesting alternatives to full-
shift sampling. Several commenters suggested that miners could be
monitored only during the loudest portion of their work shift, assuming
that this portion was predictable. Under
[[Page 49588]]
this suggested approach, if monitoring during the loudest portion of
the work shift did not indicate an overexposure, a full-shift
measurement would be unnecessary. One commenter wanted MSHA to specify
that the noise measurement be conducted for at least two-thirds of the
work shift, because this commenter believed that a mine operator cannot
always monitor a miner for the complete work shift, and because two-
thirds of a work shift would provide sufficient information to
accurately characterize the shift.
MSHA noted in the preamble to the proposal that because most mining
jobs have highly variable work tasks, high mobility, and irregular work
schedules, measurement of a miner's noise exposure for a partial shift
may not reliably project the miner's noise exposure for a full work
shift (one that is at least 8 hours), and monitoring the loudest part
of the work shift could overestimate the miner's exposure.
MSHA also received several comments suggesting other ways to
measure sound levels or a miner's noise exposure. A few commenters
suggested that if the sound level measured with an area sample
indicated that no possible overexposure exists, a full-shift
measurement would be unnecessary. A few commenters suggested that the
final rule require a 40-hour multiple-shift sampling period in order to
better define a representative work exposure.
The monitoring requirements of the final rule are intended to be
highly performance-oriented. The final rule simply requires that mine
operators effectively evaluate a miner's noise exposure to determine
compliance with part 62.
To be consistent with this performance-oriented approach, the
language of this section of the final rule has been revised from the
proposal to require that the miner's dose determination reflects the
miner's full shift. This means that the mine operator has flexibility
in determining a miner's noise dose, and may choose to use a method
that does not necessitate sampling over the course of the entire shift.
For example, if a miner who works an eight-hour shift typically
spends four hours in a noisy area of the mine and the other four hours
in a quiet area, such as a mine office, the mine operator may choose to
sample the miner's noise exposure only during the four-hour period that
the miner is exposed to higher noise levels. In such a case, the mine
operator would have a reasonable basis for concluding that a full-shift
measurement is not needed to verify that the miner is not being
overexposed. Mine operators are free to select the sampling methodology
that is appropriate for their mines. However, mine operators should be
aware that a full work shift sample is typically more indicative of a
miner's noise exposure than is a partial-shift sample, and that mine
operators are responsible under the final rule for ensuring that miners
are protected from exposures in excess of the permissible exposure
level. Mine operators also must ensure that miners with noise exposures
that equal or exceed the action level must be enrolled in a hearing
conservation program.
MSHA therefore recommends that, when a personal noise dosimeter is
used for measurement, the determination be made over the duration of
the entire shift. Alternatively, if another dose determination
methodology is used, it must reflect the noise dose for the miner's
full shift. For example, the multiple-shift sampling approach
recommended by a commenter would produce results that are not relevant
to compliance with the standard, which is based upon a miner's exposure
over a full work shift.
One commenter expressed concern that personal noise dosimeters
would only integrate sound levels for 8 hours. On the contrary, it has
been MSHA's experience that personal noise dosimeters integrate sound
levels for at least 8 hours, or until the personal noise dosimeters are
either turned off or placed in a standby mode. Therefore, personal
noise dosimeters can measure a miner's noise exposure during an
extended shift.
Criterion Level and Exchange Rate
Section 62.110(b)(2)(iv) of the final rule remains unchanged from
proposed Sec. 62.120(a)(3)(iii) and establishes the criterion level of
90 dBA. Because commenters who referenced the criterion level did so in
the context of the permissible exposure level, their comments are
addressed under Sec. 62.130 of the preamble.
Section 62.110(b)(2)(iv) of the final rule also adopts the 5-dB
exchange rate, which was proposed in Sec. 62.120(a)(3)(iii). The
exchange rate is the change in sound level which corresponds to a
doubling or a halving of the exposure duration. For example, using a 5-
dB exchange rate, a miner who receives the maximum permitted noise dose
over an 8-hour exposure to 90 dBA would have accumulated the same dose
as a result of only a 4-hour exposure at 95 dBA, or 2-hour exposure at
100 dBA. If the exchange rate were reduced to 3 dB, a miner would
receive the same dose with a 4-hour exposure at only 93 dBA or a 2-hour
exposure at 96 dBA. In the preamble to the proposal, MSHA specifically
sought comments on changing the exchange rate from 5 dB to 3 dB.
Many commenters favored the 5-dB exchange rate because they thought
that implementing a 3-dB exchange rate was infeasible. Some of these
commenters, believing that a 5-dB exchange rate is based on work shifts
with intermittent noise exposure, felt that a 5-dB exchange rate is
more appropriate because mining noise exposures are generally
intermittent. A few of the commenters believed the 3-dB exchange rate
was not supported by scientific evidence. Some commenters also
suggested that, if the 5-dB exchange rate is retained, the permissible
exposure level should be lowered to 88 or 85 dBA, and that either a 3-
dB exchange rate apply above 115 dBA, or mine operators be prohibited
from implementing administrative controls to control exposures to sound
levels exceeding 100 or 105 dBA.
As indicated in the preamble to the proposal, MSHA evaluated the
impact a 3-dB exchange rate would have on the measured noise exposure
of miners working in U.S. metal and nonmetal mines. Federal mine
inspectors collected measurements during the course of their regular
inspections using personal noise dosimeters, collecting data using 5-dB
and 3-dB exchange rates simultaneously.
The measurements for a 5-dB exchange rate were made using a 90-dBA
threshold, while the 3-dB exchange rate data were obtained without a
threshold, allowing for analysis of data at values below a
TWA8 of 90 dBA, which is not possible with a 90-dBA
threshold. The results of the study indicated the selection of an
exchange rate substantially affects the measured noise exposure in the
following ways:
(1) The percentage of miners whose noise exposures would be
calculated to exceed a TWA8 of 90 dBA permissible exposure
level (or an Leq,8 of 90 dBA in the case of a 3-dB exchange
rate) increased from 26.9% to 49.9% when the exchange rate changed from
5 dB to 3 dB;
(2) Switching to a 3-dB exchange rate and setting the permissible
exposure level at an Leq,8 of 85 dBA would increase the
percentage of miners whose exposure is out of compliance with the
permissible exposure level from 67.6% to 85.5%; and
(3) Additional engineering and administrative noise controls would
be required under the 3-dB exchange rate, and they would be more
expensive.
[[Page 49589]]
Although the Agency has not compiled similar data for coal mines,
MSHA has concluded that the consequences of adopting a 3-dB exchange
rate would be similar. This conclusion is based on the similarity of
mining operations and equipment and the consistency of the exposure
data at the 5-dB exchange rate in either sector of the mining industry.
Several commenters advocated the use of a 3-dB exchange rate,
citing scientific studies to support their position.
In the preamble to the proposed rule, MSHA noted its awareness of a
consensus in the recent literature that noise dose actually doubles
more quickly than measured by the 5-dB exchange rate, and that there
appears to be a consensus for an exchange rate of 3 dB. However, the
Agency also noted in the preamble to the proposal that it intended to
retain the proposed 5-dB exchange rate because of feasibility
considerations.
Under the Mine Act, MSHA is required, when promulgating a standard,
to make a reasonable prediction, based on the ``best available
evidence,'' that the industry can generally comply with the standard
within an allotted period of time. The Agency must demonstrate a
reasonable probability that the typical mine operator will be able to
develop and install controls meeting the standard. MSHA noted in the
preamble to the proposal that the exposure data, in conjunction with
the study referenced above, suggested that it would be difficult for
MSHA to make such a showing in proposing a 3-dB exchange rate. This is
particularly true at smaller mines, where many mines would not have
enough employees to allow implementation of certain administrative
controls, such as job rotation. Although some commenters were not
persuaded by the discussion in the preamble to the proposal that a 3-dB
exchange rate would be infeasible in the mining industry, MSHA received
no additional data from commenters contradicting this determination.
Additionally, MSHA believes that any decision on the appropriate
exchange rate for noise dose determinations is closely linked to a
decision on the appropriate permissible exposure level, and should be
considered as part of that process. As indicated in the preamble
discussion of feasibility and under Sec. 62.130, MSHA has concluded
that the existing permissible exposure level should not be revised at
this time. Revision of the applicable exchange rate should also be
deferred. Accordingly, MSHA continues to conclude that it would be
extremely difficult and prohibitively expensive for the mining industry
to comply with the existing permissible exposure level with a 3-dB
exchange rate, using currently available engineering and administrative
noise controls. MSHA therefore cannot demonstrate that implementation
of such an exchange rate would be feasible. However, the Agency will
continue to monitor the feasibility of adopting a 3-dB exchange rate.
A-Weighting and Slow Response Instrument Setting
Section 62.110(b)(2)(v) of the final rule, like
Sec. 62.120(a)(3)(iv) of the proposed rule, requires that instruments
used for measuring noise exposures be set for the A-weighting network
and slow response. OSHA also uses the A-weighting network and the slow
response for evaluating exposure to noise.
Weighting networks were originally designed to approximate the
loudness-level-sensitivity of the human ear to pure tones. The human
ear does not respond uniformly to all frequencies of tones. At low
sound pressure levels (e.g., 50 dB), the ear is less responsive to low-
and high-frequency tones. At higher sound pressure levels (that is, 90
dB), the ear responds more uniformly to low- and high-frequency tones.
Low-frequency tones are, however, less damaging to hearing than mid-
frequency tones.
Several weighting networks have been developed to take these
differences into account and have been designated as A, B, and C. Early
researchers suggested the use of the A-weighting network when the sound
pressure level was less than 55 dB; the B-weighting network between 55
and 85 dB; and the C-weighting network for sound pressure levels
exceeding 85 dB (Scott, 1957). Since that time, however, a scientific
consensus has developed on the use of the A-weighting network to
measure occupational noise exposure at all sound levels.
The acoustical performance of the A-weighting network has been
defined in consensus standards established by the American National
Standards Institute (ANSI). ANSI S1.4-1983, ``American National
Standard Specification for Sound Level Meters,'' and ANSI S1.25-1991,
``American National Standard Specification for Personal Noise
Dosimeters,'' define the identical A-weighting networks for the
respective instruments. No comments were received recommending the use
of a weighting network other than the A-weighting network.
Response time is a measurement of the speed at which an instrument
responds to a fluctuating noise. There are several instrument response
times that have been standardized fast, slow, impulse, exponential, and
peak. The quickest response is the peak response and the slowest is the
slow. Originally the slow response (1000 milliseconds) was used to
characterize occupational noise exposure, because reading the needle
deflections on a meter in rapidly fluctuating noise was easier. Using
the fast response (125 milliseconds) resulted in needle deflections
that were too difficult for the human eye to follow. The slow response
was in use to characterize noise exposure at the time when most damage
risk criteria were developed. As a result, both the previously
referenced ANSI S1.4 and S1.25 instrumentation standards for sound
level meters and personal noise dosimeters, respectively, contain
specifications for the slow response.
Some commenters suggested that MSHA adopt the fast response for all
measurements. Others objected to the use of the slow response only with
personal noise dosimeters, where, they believe, the slow response
overestimates the noise exposure for fluctuating or intermittent noise.
These commenters had no objection to using the slow response with sound
level meters where the effect of intermittency could be taken into
account. One commenter stated MSHA should use the fast response to
conform with an international consensus standard.
However, the majority of the scientific community and most
international regulatory authorities accept slow response as the
appropriate measurement parameter for characterizing occupational noise
exposures, and it has been used by the U.S. Department of Labor since
the adoption of the Walsh-Healey Public Contracts Act noise regulations
of 1969 to measure occupational noise exposure. Based upon data
included in Part V, Material Impairment, which showed good correlation
between hearing loss and A-weighted noise exposures, and the accepted
use of the slow response setting, the final rule adopts the proposed A-
weighting and slow response settings for instruments that are used to
determine a miner's noise exposure.
Observation of Monitoring
Paragraph (c) of Sec. 62.110 of the final rule, like proposed
Sec. 62.120(g), requires mine operators to provide affected miners and
their representatives with an opportunity to observe any monitoring
required under this rule. In addition, the
[[Page 49590]]
final rule requires mine operators to give prior notice to miners and
their representatives of the dates and times when the mine operators
intend to conduct the monitoring. MSHA has no existing requirement in
this area.
This provision is consistent with section 103(c) of the Mine Act,
which requires that regulations issued by MSHA for monitoring or
measuring toxic materials or harmful physical agents such as noise
provide miners or their representatives with an opportunity to observe
such monitoring. MSHA views mine operator monitoring as an important
component in operators' efforts to protect the hearing of the miners
they employ. The primary purpose of operator monitoring is protection
of miners. Monitoring provides operators with an awareness of the
miners' noise exposures at their mines and the specific sound levels to
which miners are exposed. In addition, it reminds operators of their
obligations to reduce excessive sound levels to ensure protection of
miners.
The Agency received a number of comments on this aspect of the
proposal. Several commenters supported providing miners and their
representatives with an opportunity to observe required monitoring.
Several commenters stated that miners should be paid when observing
monitoring. On the other hand, many commenters stated that section
103(f) of the Mine Act, which requires mine operators to compensate
representatives of miners who accompany MSHA inspectors on inspections,
does not apply to observation of operator monitoring because it is not
conducted as part of an MSHA inspection. MSHA agrees. Section 103(f) of
the Mine Act requires ``walkaround pay'' when a representative of
miners who is employed by the operator accompanies an MSHA inspector
during an inspection of the mine. Section 103(f) does not authorize
``walkaround pay'' for time spent by a representative of miners
observing a mine operator's monitoring program. The final rule,
therefore, does not include a requirement for mine operators to
compensate a representative of miners for participating in the
observation of monitoring.
One commenter stated that by requiring mine operators to provide
miners' representatives with an opportunity to observe noise
monitoring, MSHA is improperly expanding the scope of section 103(c) of
the Mine Act, which addresses monitoring of ``toxic materials'' or
``harmful physical agents.''
MSHA has consistently considered noise to be a ``harmful physical
agent'' covered under section 103(c) of the Mine Act. The legislative
history of the Federal Coal Mine Health and Safety Act of 1969,
Conference Report 91-761, indicates that excessive noise was one of the
harmful physical agents that Congress anticipated would be the subject
of health standards. Also, the legislative history of the Federal Mine
Safety and Health Act of 1977 reveals that NIOSH had conducted studies
on ``toxic substances,'' including substances in metal and nonmetal
mines, and had developed criteria documents on those substances, which
included noise. In addition, a U.S. Circuit Court of Appeals has
determined that noise is a ``harmful physical agent'' under the
Occupational Safety and Health Act. Forging Industry Association v.
Secretary of Labor, 773 F.2d 1436, 1444 (4th Cir. 1985). Accordingly,
MSHA has concluded that noise falls within the scope of section 103(c)
of the Mine Act, and that MSHA has the authority to establish
regulations that provide miners and their representatives access to
noise exposure monitoring conducted by mine operators.
Several commenters recommended that the Agency substitute the term
``representatives of miners'' for ``their representatives,'' because
they believed that it was important to clarify that the representatives
referred to in this section are miners' representatives designated
under MSHA's regulations at 30 CFR part 40.
Under part 40, the definition of ``representative of miners''
includes `` `representatives authorized by the miners,' `miners or
their representative,' `authorized miner representative,' and other
similar terms as they appear in the Act.'' Consequently, MSHA believes
that the terminology used in the final rule is sufficient to indicate
that the ``representative'' referred to in this section is a ``miner's
representative'' designated under part 40. The final rule therefore
does not adopt the suggestion of commenters.
Many commenters were opposed to allowing both miners and their
representatives to observe operator monitoring. Several commenters
stated that because most mine operators use personal noise dosimeters,
which must be placed on the miner, the miner is effectively
participating in the monitoring, and is told of the results at the end
of the day. These commenters believe that requiring a miners'
representative to observe would be redundant and result in adversarial
relations between labor and management. The final rule does not adopt
this comment, because MSHA broadly interprets the opportunity for
observation of this monitoring to extend to both miners and their
representatives, consistent with the underlying purposes of the Mine
Act. Further, participation by miners and their representatives will
enhance miner safety and health awareness and contribute to greater
understanding of the nature and extent of the noise hazard.
In its Preliminary Regulatory Impact Analysis for the proposed
rule, MSHA used the terms ``off-duty'' and ``non-duty'' miners in the
context of observation of monitoring. One commenter raised concerns
about MSHA's use of these terms, and questioned whether MSHA intended
to create a new category of miner. MSHA did not intend by using this
term to create a new category of miner. Instead, MSHA used the two
terms interchangeably to refer to a miner who works on a shift other
than the one where he or she is observing the monitoring. To avoid any
confusion, MSHA uses only the term ``off-duty'' miner in the final
Regulatory Economic Analysis.
One commenter was opposed to letting an off-duty miner or miners'
representative on the property to observe noise monitoring. The
commenter stated that this raised a number of issues, including:
Who would be responsible for escorting these people around the
property? Is the operator supposed to provide them with
transportation? What happens if they should get injured? They are
off duty but still on the mine property. How would this be
classified?
The final rule does not specify how the requirement of observation
of monitoring must be implemented. Instead, mine operators have the
flexibility to determine, based on an assessment of their unique mining
operations, how to best implement this provision. MSHA does not believe
that it is either necessary or in the best interest of miners' health
to impose additional restrictions on who should be allowed to observe
monitoring, or how the observation of monitoring should be conducted.
Most if not all of the hypothetical situations raised by the commenter
could occur in contexts other than the observation of monitoring. MSHA
expects that these questions will be resolved through the labor-
management processes already in place.
Several commenters were concerned that allowing miners'
representatives to observe could place the miners' representative in
unsafe positions,
[[Page 49591]]
especially in the case of single occupancy equipment such as a shuttle
car, scraper, or bulldozer. The Agency does not intend that the
exercise of the right to observe noise monitoring will expose miners or
their representatives to unsafe working conditions. The purpose of
observation by the miners' representative is to ensure that the miner
is operating the equipment under normal working conditions and that the
instrumentation is being used properly. Thus, in those cases where
mobile, single-occupancy equipment is involved, the miners'
representative can observe the monitoring from a safe distance.
Several commenters questioned whether the number of observers or
the observation time would be limited. The final rule does not limit
the number of miners, their representatives, or time spent observing
monitoring. Therefore, under the final rule miners have the option of
observing monitoring for the full shift, part of the shift, or not at
all.
MSHA considers field calibration of the instruments, and any
recording of results to be included within the right of observation.
MSHA believes that miners who observe operator's monitoring procedures
gain insight into the nature and extent of the noise hazard, and are
more likely to become more involved in the hearing conservation
program. This involvement should increase the motivation for proper use
of hearing protectors, thereby increasing the effectiveness of the
program and allowing them to share their knowledge with their fellow
miners, thus improving overall health at the mine.
Paragraph (c) also requires mine operators to give prior notice to
affected miners and their representatives of the date and time they
intend to conduct monitoring. One commenter supported the provision as
proposed, stating that it is an acceptable and reasonable practice.
Several commenters stated that requiring notification of both
miners and their representatives of operator monitoring would be unduly
burdensome, and would not enhance health and safety. One commenter
recommended that MSHA adopt OSHA's provision, which simply requires
employees or their representatives to be afforded an opportunity to
observe noise measurements.
The Agency concludes that miners and miners' representatives need
time to make necessary preparations to exercise their right to observe
monitoring, and that notification is necessary to achieve this goal.
Notification may be needed in order to alert the miner and the miners'
representative of the need to come to the mine on an off-shift, or to
arrive early at the mine to observe field calibration of
instrumentation. Other commenters stated that providing prior notice
compromises integrity and the ability of the mine operator to inspect
for safety or conduct health surveys for the benefit of workers.
Because miners and their representatives will only be observing
monitoring and not actually conducting monitoring, prior notice will
not compromise the integrity of the monitoring. Nonetheless, MSHA
emphasizes that the exercise of the right to observe monitoring should
not interfere with the monitoring process.
Several commenters stated that requiring mine operators to provide
prior notification of monitoring would interfere with spot area
sampling. Another commenter stated that providing prior notice is not
always possible, such as during the introduction of a new piece of
equipment or machinery. Several commenters also questioned whether MSHA
intended to require mine operators to give prior notice of all operator
monitoring and whether miners and their representatives should have the
opportunity to observe any and all such monitoring. These commenters
suggested that the final rule require that the mine operator provide
notice and the opportunity for observation only of a reasonably
representative number of such monitoring events.
The final rule does not require prior notice of such activities as
spot area sampling or measurement of the sound produced by a new piece
of equipment before the equipment is placed into service. Under the
final rule, mine operators are required to give prior notice only of
monitoring that is conducted to determine whether a miner's noise dose
equals or exceeds the action level, or exceeds the permissible exposure
level or the dual hearing protection level.
Additionally, paragraph (c) of this section of the final rule, like
the proposal, does not specify a required method of notification. One
commenter supported the provision because of its flexibility with
respect to such notification. Another commenter stated that for notice
to be unambiguous it must be in writing and either mailed or posted on
the mine bulletin board. Several commenters also questioned what would
constitute adequate prior notice. For example, one commenter supported
requiring prior notice but stated that the notice should be given at
least five days in advance so that miners and their representatives had
sufficient time to prepare to observe. Several commenters, on the other
hand, stated that requiring five days' written notice would be
extremely restrictive and would reduce the flexibility of the vast
majority of mine operators to adjust to a changing work environment.
MSHA agrees with these commenters, and the final rule, like the
proposal, requires prior notice to miners and their representatives but
does not specify how this notice is to be given. The Agency considers
``prior notice'' under the final rule to be a reasonable amount of time
which is practical under the circumstances to allow miners and their
representatives to exercise the opportunity to observe monitoring.
Under the final rule, the operator may use any method of notification--
including oral, written, and posted notification--which effectively
informs miners and their representatives of intended monitoring. For
example, some mine operators may use informal talks as an effective
means of keeping miners informed on a day-to-day basis. Other mine
operators may elect to inform miners in writing to avoid confusion and
to demonstrate compliance. Finally, some mine operators may elect
posting because miners know where the bulletin board is located and
because posting is an accepted and well established method of
disseminating information at mine sites. Any of these methods would be
an effective means of providing the notification required under the
final rule. Therefore, this provision is adopted as proposed.
Miner Notification
Paragraph (d) of Sec. 62.110, like Sec. 62.120(f)(2) of the
proposal, requires notification when a miner's noise exposure equals or
exceeds the action level or exceeds the permissible exposure level or
the dual hearing protection level. Whenever a miner's exposure is
determined to exceed any of the levels established in Secs. 62.120,
62.130, or 62.140 of this part, based on exposure evaluations conducted
either by the mine operator or by MSHA, and the miner has not received
notification of exposure at such level within the prior 12 months, the
mine operator must notify the miner in writing within 15 calendar days
of the exposure determination and of the corrective action being taken.
The mine operator must maintain a copy of any such miner notification,
or a list on which the relevant information about that miner's
notification is recorded, for the duration of the affected miner's
exposure at or above the action level and for at least 6 months
thereafter.
[[Page 49592]]
The notification requirement in the final rule is consistent with
section 103(c) of the Mine Act, which states in pertinent part:
Each operator shall promptly notify any miner who has been or is
being exposed to * * * harmful physical agents * * *at levels which
exceed those prescribed by an applicable mandatory health or safety
standard promulgated under section 101 * * *and shall inform the
miner who is being thus exposed of the corrective action being
taken.
Several commenters supported the requirement for written
notification and requested that MSHA also require written notification
to the miners' representative. Other commenters suggested that the
required written notification also be submitted to MSHA. One commenter
believed that notification should not be required if all miners are
enrolled in a hearing conservation program. A number of other
commenters questioned the need to notify affected miners in writing.
Some of these commenters stated that posting the exposure determination
results would be sufficient notification for the affected miner and any
other miners working in the area. Other commenters believed that the
mine operator should be able to choose any method of notification as
long as the miner received the required notice. One commenter supported
the notification requirement, and suggested including a statement
concerning the mandatory use of hearing protectors, if appropriate.
The notification provided for in this paragraph is required under
section 103(c) of the Mine Act. In addition, MSHA has determined that
such notification is an integral part of the protection afforded to
miners whose noise exposures may be injurious to their hearing. The
Agency also believes that in order to ensure that all affected miners
are properly notified and informed of the additional precautions
necessary to protect their hearing, such notification must be in
writing and must be recorded. Noise exposures at or above the action
level present a significant risk of material impairment (as discussed
under Part V of this preamble, Material Impairment). Miners must be
notified when their noise exposures are at or above the action level
because of this risk, and also because such exposures trigger specific
corrective actions by the mine operator under the final rule--training
miners, providing miners with hearing protectors, and offering miners
audiometric testing. Notification alerts miners of the need to
conscientiously wear their hearing protectors and may also provide some
additional incentive for participation in the voluntary audiometric
testing program.
MSHA has also concluded, and the final rule reflects, that the
notification should be in writing. This ensures that the miner
understands the exposure determination and the corrective actions being
taken.
Several commenters agreed with the approach taken by the proposal
that would make notification unnecessary if the mine operator had
already notified the affected miner of the exposure level during the
past 12 months. One of the primary objectives of notification, as
explained above, is to ensure that miners are aware of the importance
of taking the additional precautions to protect their hearing. If a
miner's noise exposure has not changed, there would be no additional
benefit to be gained by repeated notification. In any case, annual
retraining is required for those miners whose noise exposures continue
to equal or exceed the action level.
Many commenters took issue with the proposed time frame of 15
calendar days for mine operators to notify a miner in writing that the
miner's noise exposure exceeded any limit prescribed in proposed
Sec. 62.120. Most of the commenters believed that the 15-day time frame
was too restrictive and suggested that this period be extended. Among
the reasons given in support for this suggestion were delays in
obtaining exposure reports from consultants and employee vacations.
Commenters recommended time frames for notification that ranged from 15
to 60 days. A few recommended that the mine operator be allowed to
determine the appropriate time frame. One commenter, however, suggested
that the time allowed for notification be reduced to 24 hours for
exposure determinations and 7 days for reporting the mine operator's
plan of corrective actions to reduce the noise exposure. One commenter
was opposed to the notification requirement, because OSHA's noise
standard lacks this provision.
MSHA believes that timely notification is an important first step
in protecting miners from excessive noise exposure. The final rule
therefore adopts the proposed requirement that the mine operator notify
the miner within 15 calendar days of any noise exposure that equals or
exceeds the action level or exceeds the permissible exposure level or
the dual hearing protection level. The 15-day time frame is adopted
from the proposal based on MSHA's determination that 15 days affords
the mine operator sufficient time to provide this notification. This
determination takes into account the fact that administrative delays
may arise, but balances these delays against the need for miners to be
alerted promptly of potentially harmful noise exposures, and to be
informed of the steps that are being taken to remedy the situation.
The proposal would have required that records of required
notification be maintained at the mine site. Several commenters
requested that the final rule allow the required records to be
maintained at a central location, such as a corporate office, to ease
the burden of managing the records of multiple mine sites. Commenters
also stated that they believed this would make it easier for MSHA to
review the required records for these sites.
As stated in Part III of this preamble, MSHA agrees with the points
made by these commenters, particularly in light of the fact that
electronic records are common in the mining industry, and that many or
all of a mine's records may be stored on computer at a centralized
location. The final rule therefore does not adopt the proposed
requirement that these records be maintained at the mine site, and does
not specify a location where the records must be maintained. However,
the records must be stored in a location that will allow the mine
operator to produce them for an MSHA inspector within a relatively
short period of time, which in most cases will be no longer than one
business day.
Commenters also presented their views on record retention. Under
the proposal, records of miner notification would have been required to
be retained for the duration of the miner's exposure above the action
level and for 6 months thereafter. A few commenters believed a
requirement for record retention was unnecessary. Other commenters
believed the records should be maintained for longer than 6 months
beyond the duration of exposure. The recommended record retention time
ranged up to 40 years. Several commenters believed the exposure records
should be treated as medical records. Another commenter believed the
exposure records should be retained for at least the duration of the
affected miner's employment.
MSHA has concluded, and the final rule reflects, that it is
sufficient for the mine operator to retain exposure notification
records for the duration of the miner's exposure at or above the action
level and for at least 6 months thereafter. The retention period
provided for by the final rule calls for records to be retained for a
relatively short period of time after cessation of exposure at or above
the action level, minimizing the recordkeeping burden
[[Page 49593]]
on mine operators. The extended record retention periods recommended by
some commenters would be appropriate if the records were to be used for
epidemiological purposes. However, the records required to be
maintained under this section of the final rule are not the type of
dose determinations that would be suitable for epidemiological
analysis. Additionally, unlike the effects of exposure to carcinogens,
hearing loss due to noise exposure manifests itself shortly after the
exposure. The effects of exposure to carcinogens may not be seen until
years after exposure. Requiring the retention of noise exposure records
for many years therefore serves no purpose. The final rule therefore
does not adopt this comment.
Warning Signs
The proposed rule did not include any requirements for the posting
of warning signs at mines to alert miners of noise hazards that may be
present. In the preamble to the proposed rule, MSHA acknowledged the
possible value of warning signs but concluded that the constantly
changing mining environment presents significant obstacles to effective
posting. MSHA therefore determined that the miner training requirements
of the final rule will ensure that miners are sufficiently informed of
the noise hazards to which they may be exposed.
Although MSHA did not solicit comments in the proposed preamble on
warning signs, several commenters did express their opinions on this
issue. Some commenters believed the warning signs should be required,
other commenters believed posting signs is appropriate only where
hearing protectors must be worn. Several other commenters believed that
posted warning signs were not effective because they were ignored.
MSHA continues to conclude that the posting of warning signs should
be optional and is best left to the discretion of the operator. As
stated in the proposed preamble, MSHA expects that many mine operators
will voluntarily post signs to indicate areas of the mine where hearing
protectors should be worn.
Section 62.120 Action Level
Like the proposal, Sec. 62.120 of the final rule requires mine
operators to take certain actions when a miner's noise exposure equals
or exceeds an 8-hour time-weighted average of 85 dBA during any work
shift. Under proposed Sec. 62.120(b)(1) and (b)(2), mine operators
would have been required to provide training to a miner exposed above
the action level, provide hearing protection to such miner, and enroll
the miner in a hearing conservation program that included audiometric
testing.
Under the final rule, the mine operator is required to enroll a
miner in a hearing conservation program that complies with Sec. 62.150,
which consolidates the elements of a hearing conservation program into
a single section. These elements include a system of monitoring that
complies with Sec. 62.110; the use of hearing protectors under
Sec. 62.160; audiometric testing under Secs. 62.170 through 62.175;
training under Sec. 62.180; and recordkeeping under Sec. 62.190.
Although the language of the final rule differs from that of the
proposal, the requirements are essentially the same. This
reorganization of the rule was made in response to commenters who
recommended that the final rule take a more traditional approach to the
hearing conservation program. This issue is discussed in greater detail
under Sec. 62.150 of the preamble.
The final rule requires that the mine operator enroll a miner in a
hearing conservation program if, during any work shift, the miner's
noise exposure equals or exceeds a TWA8 of 85 dBA or,
equivalently, a dose of 50%. Like the proposal, the final rule requires
that all sound levels from 80 dBA to at least 130 dBA be integrated
into the noise exposure determination for the action level. This
integration range requirement is identical to the one in OSHA's noise
standard. Sound levels below the 80-dBA threshold are not integrated
into the noise exposure measurement. It should be noted that a noise
dose determination for the permissible exposure level requires the use
of a 90-dBA threshold. In practice, when a noise exposure measurement
is performed, either two separate noise dosimeters (one set for an 80-
dBA threshold for the action level, and one set for a 90-dBA threshold
for the permissible exposure level), or a single dosimeter with dual
threshold capabilities would be required.
The final rule clarifies that the mine operator must enroll a miner
in a hearing conservation program if during any work shift the miner's
exposure equals or exceeds the action level. The proposal would have
provided that the mine operator take action if the miner's exposure
exceeded the action level. A number of commenters recommended this
clarification to ensure that the final rule was consistent with OSHA's
noise standard. The final rule has been revised accordingly.
Many commenters supported the concept of an action level but wanted
MSHA to be consistent with the requirements of OSHA's noise standard.
In particular, the commenters supported the proposed requirement for
taking initial protective action at the level of 85 dBA, and the
threshold of 80 dBA for integrating all sound levels when computing the
action level. These commenters stated that the 85-dBA action level and
80-dBA threshold were more protective of miners and based on the best
available scientific information, and were also compatible with OSHA's
noise standard.
However, a number of commenters were opposed to the proposed
establishment of an action level. Several commenters questioned the
appropriate action level, stating that the level should be set at a
TWA8 of 90 dBA. Some of these commenters believed that noise
control technology for complying with an action level of a
TWA8 of 85 dBA is not available, and that an allowance for
the use of hearing protectors should be made when determining
compliance with the action level.
MSHA's determination that it is necessary to establish an action
level in the final rule is based on several considerations. The first
and most important of these factors is that MSHA's review of the
scientific literature and Agency risk data, coupled with the comments
submitted under this rulemaking, indicates that there is a significant
risk of material impairment to miners from a lifetime of exposure to
noise at a TWA8 of 85 dBA, as discussed in the preamble
section on material impairment. For that reason, miners need to be
protected from noise exposures at or above this level. However, as
explained in greater detail under the preamble discussion of the
permissible exposure level, the Agency has determined that it is not
feasible at this time for the mining industry to comply with a lower
permissible exposure level. The issue of risk to miners is discussed in
greater detail under the material impairment section of this preamble.
MSHA has nonetheless concluded that it is necessary to provide
miners with protection at this level in order to reduce instances of
new hearing loss and to prevent the progression of existing hearing
loss. Agency data reveal that a miner's risk of developing a
significant hearing loss drops by approximately half under the new
action level requirements of the final rule.
As stated above, the hearing conservation program in which miners
are enrolled under the final rule must comply with Sec. 62.150, and
must address the use of hearing protectors, provide
[[Page 49594]]
miners with audiometric testing, and provide effective monitoring of
their noise exposures. Although some commenters disputed the
effectiveness of hearing conservation programs, MSHA has reviewed the
research concerning such programs, especially the OSHA hearing
conservation program, and has determined that hearing conservation
programs are effective in protecting workers.
Under the final rule, a miner who is exposed to noise at or above
the action level must, as part of the enrollment in a hearing
conservation program, receive specialized training that addresses the
hazards of noise and protective methods. Specific topics that must be
addressed by this training include the effects of noise on hearing, the
purpose and value of wearing hearing protectors, and the mine
operator's and miner's respective tasks in maintaining noise controls.
Additionally, a miner who is enrolled in a hearing conservation
program must be provided with properly fitted hearing protectors and
receive training on their use. Although MSHA has concluded that the
difficulty in determining the noise reduction provided by a given
hearing protector makes it inappropriate to adjust a dose determination
on that basis, hearing protectors can serve as an effective means of
protecting miners from the hazards of excessive noise.
Miners enrolled in a hearing conservation program must also be
offered annual audiograms at no cost. Annual audiometric testing will
enable mine operators and miners to take protective measures in
response to identified early hearing loss, and enable the prevention of
further deterioration of hearing.
As discussed in the preamble to the proposed rule, a number of
studies have addressed the effectiveness of hearing conservation
programs in preventing hearing loss. Many of the studies indicate that
a hearing conservation program can be effective in reducing and
controlling noise-induced hearing loss, but only if management and
employees strictly follow the program requirements.
MSHA has therefore concluded that enrollment in a hearing
conservation program for miners whose noise exposure equals or exceeds
the action level can protect miners from occupational hearing loss.
Consistent with this determination, the final rule requires these
miners to be enrolled in such a program. However, as stated above, the
effectiveness of the program in protecting miners depends on the
commitment of mine operators and miners to conscientious compliance
with the requirements of the program.
MSHA agrees with the commenters who stated that noise control
technology may not always be available to reduce the noise exposure
below the action level. The lack of available technology was one of the
bases for MSHA's determination that a permissible exposure level of a
TWA8 of 85 dBA is not feasible for the mining industry at
this time. Consistent with that determination, the final rule does not
require that noise controls be implemented to reduce miners' noise
exposures to the action level. Instead, mine operators are required to
enroll miners in a hearing conservation program if the miners'
exposures reaches the action level.
Some commenters stated that the proposed action level requirement
would create unnecessary paperwork and cost burdens for mine operators.
MSHA has evaluated all of the paperwork provisions in the final rule
and has chosen the alternatives which impose minimal paperwork burdens
on the industry. Although the final rule does eliminate some existing
paperwork requirements, MSHA believes that the remaining paperwork
provisions in the final rule are necessary for improving protection for
miners.
Many commenters supported the proposed integration of all sound
levels from 80 dBA to at least 130 dBA when computing the action level.
They stated that this was consistent with OSHA's noise standard, would
be more protective of miners, and would allow resources to be directed
at the worst exposures. Other commenters opposed the proposed
integration range of 80 dBA to 130 dBA, stating that it would
unnecessarily inflate the calculated noise dose and dramatically
increase the time-weighted average daily exposure dose. Based on a
review of the entire record, the final rule reflects the proposed
integration range of 80 dBA to at least 130 dBA as appropriate for
protecting miners from experiencing additional hearing impairment.
MSHA notes that the requirements in Sec. 62.110(b) of the final
rule, which apply to miners' dose determinations, must be complied with
when a noise exposure assessment is conducted for the action level.
This means that, in addition to integrating all sound levels over the
appropriate range, the determination must be made without adjustment
for hearing protectors; must reflect the miner's full work shift; must
use a 90-dB criterion level and a 5-dB exchange rate; and use the A-
weighting and slow response instrument settings.
The requirements in proposed Sec. 62.120(b)(2) that the mine
operator provide hearing protectors to the affected miners and ensure
their use, if it would take more than 6 months to conduct the baseline
audiogram or if a miner is determined to have incurred a standard
threshold shift, have been adopted in Sec. 62.160(c)(1) and (c)(2) of
the final rule.
Additionally, as indicated under Sec. 62.160 of the preamble,
proposed Sec. 62.120(b)(3), which would have required that the mine
operator provide any miner who has been exposed to noise above the
action level with hearing protectors upon request, is not specifically
adopted in the final rule. Because the final rule requires that such a
miner be enrolled in a hearing conservation program, which must include
the provision of hearing protectors under Sec. 62.160 of the final
rule, the adoption of the proposed requirement is unnecessary.
Section 62.130 Permissible Exposure Level (PEL)
Section 62.130(a) of the final rule adopts proposed Sec. 62.130(c)
and establishes a permissible exposure level of an 8-hour time-weighted
average (TWA8) of 90 dBA, which represents no substantive
change from the existing standards. Under the final rule, a
TWA8 of 90 dBA is equivalent to a dose of 100%. The final
rule provides that no miner be exposed during any work shift to noise
that exceeds the permissible exposure level. Paragraph (a) also
provides that if during any work shift a miner's noise exposure exceeds
the permissible exposure level, the mine operator must use all feasible
engineering and administrative controls to reduce the miner's noise
exposure to the permissible level, and enroll the miner in a hearing
conservation program.
Under the current metal and nonmetal noise standard, feasible
engineering or administrative controls are required to be used when a
miner's noise exposure exceeds the permissible exposure level. The
noise reduction provided by a hearing protector is not considered in
determining a miner's exposure at metal and nonmetal mines. Under the
current coal noise standard, feasible engineering and/or administrative
controls are required to be used when a miner's exposure exceeds the
permissible exposure level.
Unlike the metal and nonmetal standard, however, the coal standard
states that required controls may include hearing protectors in
specific circumstances. Credit is also given at coal mines for the
noise reduction value
[[Page 49595]]
of hearing protectors in determining a miner's noise exposure.
The final rule specifies that mine operators must integrate sound
levels from 90 dBA to at least 140 dBA. MSHA proposed integrating sound
levels between 80 dBA and 130 dBA into the permissible exposure level,
but stated in the proposed preamble that MSHA was not recommending a
lower permissible exposure level, since it would be infeasible for the
mining industry. However, in evaluating and reviewing the rulemaking
record, MSHA has concluded that lowering the threshold of sound levels
integrated into the permissible exposure level determination for
purposes of measuring a miner's noise exposure would in fact result in
a lower permissible exposure level, something that the Agency did not
intend. The final provision is therefore less restrictive than the
proposed provision would have been, but is consistent with MSHA's
findings on feasibility.
The final rule requires that mine operators use all feasible
engineering and administrative noise controls to bring miners' noise
exposures within permissible levels. Mine operators must provide miners
with hearing protectors and ensure that the protectors are properly
used if engineering and administrative controls fail to reduce exposure
to the permissible exposure level.
Unlike the enforcement policy at metal and nonmetal mines, current
coal enforcement policy allows mine inspectors to subtract the
estimated noise reduction provided by hearing protectors when
determining a miner's noise exposure. When a coal mine operator does
receive a citation for a miner's exposure exceeding the permissible
exposure level, the operator must promptly institute engineering or
administrative controls, or both. Within 60 days of receipt of the
citation, the mine operator must submit to MSHA a plan for the
administration of a continuing, effective hearing conservation program,
which includes provisions for reducing environmental sound levels to
achieve compliance, providing hearing protectors, and pre-employment
and periodic audiograms.
The final rule now requires that mine operators in both the coal
sector and metal and nonmetal sectors use all feasible engineering and
administrative controls to reduce a miner's noise exposure to the
permissible exposure level. The final rule does not place preference on
the use of engineering controls over administrative controls. MSHA
intends for mine operators to have a choice of which type of control
they use, as long as mine operators use all feasible controls necessary
to bring a miner's exposure to within the permissible exposure level.
Section 62.130(a) of the final rule also requires that if a miner's
noise exposure exceeds the permissible exposure level, the mine
operator must enroll the miner in a hearing conservation program that
complies with Sec. 62.150 of the final rule. Implementation of a
hearing conservation program is a new requirement for metal and
nonmetal mine operators and for some coal mine operators.
The final rule adopts the proposed requirement for mine operators
who use administrative controls. Those mine operators must now post
procedures for such controls on the mine bulletin board and provide a
copy of the procedures to each affected miner.
Paragraph (b) of Sec. 62.130 of the final rule, like the proposal,
provides that if feasible engineering and administrative controls fail
to reduce a miner's exposure to the permissible exposure level, the
mine operator must continue to use all engineering and administrative
controls to reduce the miner's exposure to as low a level as is
feasible.
The proposed rule would have also required that the mine operator
ensure that a miner exposed above the permissible exposure level submit
to the audiometric testing provided as part of the hearing conservation
program. The final rule, however, does not adopt this provision.
Further discussion of this issue is provided under Sec. 62.170,
addressing audiometric testing.
Section 62.130(c) of the final rule adopts the proposed provision
that at no time must a miner be exposed to sound levels exceeding 115
dBA, and also clarifies that the sound level must be determined without
adjustment for the use of hearing protectors.
Finally, proposed Sec. 62.120(d), which addressed the dual hearing
protection level, has been moved to Sec. 62.140 of the final rule.
Section 62.130 of the final rule establishes a permissible exposure
level of a TWA8 of 90 dBA, which represents no substantive
change from existing MSHA standards. The permissible exposure level is
the maximum time-weighted average sound level to which a miner may be
exposed. The exposure needed to reach the permissible exposure level
varies by sound level and duration. For example, a miner's exposure
would reach the permissible exposure level if the miner is exposed to a
sound level of 90 dBA for 8 hours or to a sound level of 95 dBA for
only 4 hours.
A number of commenters favored a permissible exposure level of a
TWA8 of 85 dBA, stating that because a significant risk of
impairment occurs at this level, miners need greater protection. MSHA
gave serious consideration to establishing a lower permissible exposure
level, including a reduced exchange rate, based on its determination
that there is a significant risk to miners of a material impairment of
health when noise exposures equal or exceed a TWA8 of 85
dBA. MSHA has concluded, however, that it is infeasible at this time
for the mining industry to achieve a more protective level by using
engineering and administrative controls. Therefore, under the final
rule, MSHA continues to require a permissible exposure level of a
TWA8 of 90 dBA, but miner protection is increased from that
provided under existing MSHA noise standards by requiring that mine
operators take protective measures at an action level of a
TWA8 of 85 dBA.
Some commenters believe that MSHA did not adequately justify that a
permissible exposure level of a TWA8 of 85 dBA was
technologically and economically infeasible. Also, one commenter
objected to considering economic infeasibility in the rationale for not
reducing the permissible exposure level to a TWA8 of 85 dBA.
Section 101(a)(6)(A) of the Mine Act directs that the Secretary's
rulemaking authority be exercised within the boundaries of feasibility,
and, as discussed in the preamble to the proposal, MSHA considered both
technological capabilities and the economic impact of a lower
permissible exposure level. MSHA made a preliminary determination, set
forth in the preamble to the proposal, that a lower permissible
exposure level was not feasible. MSHA also requested that commenters
submit relevant additional data on this issue but did not receive
adequate supporting data in response to this request.
Regarding the feasibility of a TWA8 of 85 dBA, MSHA has
found that a typical mine operator will not be able to develop and
install engineering controls at this time which will meet a permissible
exposure level lower than a TWA8 of 90 dBA. The Agency's
finding is based on the large number of mines which would require
engineering and administrative controls to reduce current exposures and
on an evaluation of noise control technology under actual mining
conditions, including retrofitting equipment, and the cost of
implementing such controls. As stated in the preamble to the proposed
rule, MSHA conducted a survey of noise exposures in the mining industry
to
[[Page 49596]]
assess the capability of the industry to comply with a permissible
exposure level lower than the current TWA8 of 90 dBA through
the use of engineering and administrative controls. The survey is
referenced as the ``dual-threshold survey'' in the section that
addresses material impairment in this preamble. Exposure data collected
by MSHA indicated that with a permissible exposure level of a
TWA8 of 85 dBA and an 80-dBA threshold, over two-thirds of
the metal and nonmetal mining industry and over three-quarters of the
coal mining industry would need to use engineering and administrative
controls to reduce current exposures (see Tables 11 and 12 in Part V of
this preamble).
A typical mine operator would not be able to develop and install
engineering controls at this time which would result in compliance with
a permissible exposure level lower than a TWA8 of 90 dBA.
Although the discussion of feasibility in this preamble references
control rooms and booths and acoustically treated cabs as being capable
of reducing exposures to below 85 dBA, MSHA has found that, for the
most part, sound levels for most mining equipment cannot be reduced to
that extent using engineering controls. This includes consideration of
retrofit noise control technology to achieve 85 dBA or less which is
not available for the majority of mining equipment without major
redesign of the equipment. The Agency's finding is based, in part, on
the evaluation of newly developed noise controls under actual mining
conditions described in ``Summary of Noise Controls for Mining
Machinery'' (Marraccini et al., 1986). Therefore, the Agency has
concluded that a typical mine operator will not be able to develop and
install engineering controls at this time that will result in
compliance with a permissible exposure level lower than a
TWA8 of 90 dBA.
In addition, the Agency has found that, where available, the cost
of implementing controls would be prohibitively expensive, based on the
large percentage of mines that would be out of compliance if a lower
permissible exposure level were to be adopted. As reflected under the
preamble discussion of feasibility, MSHA has determined that retention
of the existing permissible exposure level and threshold under the
final rule would not result in any incremental costs for engineering
controls for the metal and nonmetal sector, but would result in costs
of $1.79 million for engineering controls for the coal sector. Costs
would be incurred only by the coal mining sector under the final rule,
because hearing protectors have generally been substituted for
engineering controls in coal mines under the current regulations. Thus,
unlike the metal and nonmetal mining industry, the coal mining industry
has not exhausted the use of feasible engineering and administrative
controls to reduce noise exposures to within the permissible exposure
level of a TWA8 of 90 dBA. However, significant costs would
be incurred by the entire mining industry if the permissible exposure
level were to be reduced to a TWA8 of 85 dBA and an 80-dBA
threshold.
MSHA's ``dual-threshold survey'' shows that a significant
percentage of all mines, which would be out of compliance if a lower
permissible exposure level were adopted, would incur costs. Engineering
controls that are needed to reduce exposure levels to a TWA8
of 85 dBA are more costly than those which reduce exposure to a
TWA8 of 90 dBA. MSHA's analysis indicates that where it is
available, retrofitting equipment to achieve a permissible exposure
level of a TWA8 of 85 dBA can cost $15,000 or more per piece
of equipment. Remote control in conjunction with a fully-treated,
environmentally-controlled operator's booth can cost $10,000 or more
depending on the size of the booth and the extent of technology needed
to run the process or equipment remotely. MSHA has estimated that a
permissible exposure level of a TWA8 of 85 dBA with a 3 dB
exchange rate would cost over $54 million annually just to retrofit
equipment. However, retrofitting existing equipment alone would not
enable most mines to achieve compliance with a permissible exposure
level of 85 dBA as a TWA8. For some of these mines, capital
equipment would need to be replaced by quieter equipment capable of
meeting the lower 85 dBA level, but the cost would be enormous. For
example, where new equipment exists, depending on its size, costs range
from approximately $260,000 to $360,000 for single boom drills with
fully treated operator cabs, to approximately $2,000,000 for a 240 ton
haul truck with a fully treated operator cab. However, as previously
noted, for many types of capital equipment, no compliant replacement
equipment currently exists. Because most mines could not fully meet a
lower permissible exposure level using currently available technology,
the Agency has determined that a lower permissible exposure level would
not be feasible at this time. Accordingly, the Agency is adopting the
existing permissible exposure level of a TWA8 of 90 dBA, but
is also requiring hearing conservation measures when the exposure
reaches a TWA8 of 85 dBA.
Another commenter suggested that a long phase-in period, such as 10
years, be adopted for a permissible exposure level of a TWA8
of 85 dBA. In considering the technological and economic impact of a
new standard, MSHA must make a reasonable prediction, based on the best
available evidence, as to whether the mining industry can generally
comply with the rule within an allotted period of time. MSHA seriously
considered establishing a permissible exposure level of a
TWA8 of 85 dBA in conjunction with an extended phase-in
schedule for compliance. However, the Agency could not project, with
any reasonable certainty, when the mining industry would be capable of
developing and installing the necessary control technology to meet such
a permissible exposure level. In the preamble to the proposal, MSHA
made no assumptions about the development of new technologies to
further assist mine operators in controlling noise. The Agency
requested commenters to provide information but received none. Although
enforcement of the final rule requires that individual mine operators
only use those controls which are feasible for the particular mine
operator, MSHA is unable to demonstrate a reasonable probability that
the mining industry as a whole would be able to comply, even with a
long phase-in period.
Several commenters wanted MSHA to adjust the permissible exposure
level of a TWA8 of 90 dBA for those miners working extended
work shifts, and one commenter believed that it was important to
include extended work shifts in the definition of the permissible
exposure level. The final rule requires mine operators to determine a
miner's noise exposure for the full work shift, regardless of length of
time the miner works on the shift. MSHA acknowledges that extended work
shifts are becoming a more common practice in the mining industry and
intends for miners working on these shifts to receive the full
protection of the final rule. Sampling for a full shift is consistent
with the OSHA standard as well as current noise regulations for both
coal and metal and nonmetal mines.
Section 62.130(a) of the final rule differs from the proposal in
that a miner's exposure determination for comparison to the permissible
exposure level requires the integration of all sound levels from 90 to
at least 140 dBA. The proposal would have required integration of sound
levels from 80 to at least 130 dBA. Several commenters to the proposed
standard brought to
[[Page 49597]]
MSHA's attention that the proposed range of sound integration would
result in a lower permissible exposure level for the mining industry,
an unintended result of the rule, discussed earlier. Moreover, the
final rule's adoption of the proposed 80-dBA threshold for determining
whether miners' exposures equal or exceed the action level ensures that
miners are afforded protection at or above an exposure of a
TWA8 of 85 dBA.
Section 62.130(a) also requires that when a miner's noise exposure
exceeds the permissible exposure level, the mine operator must use all
feasible engineering and administrative controls to reduce a miner's
exposure to the permissible exposure level before relying on hearing
protectors. In addition, mine operators must establish a hearing
conservation program for affected miners.
The final rule does not place preference on the use of engineering
controls over administrative controls to protect miners exposed above
the permissible exposure level. All feasible controls, of both types if
necessary, must be implemented to reduce noise exposure to the
permissible exposure level, or to the lowest feasible level if the
permissible exposure level cannot be achieved. In response to
commenters who questioned which controls mine operators must use, MSHA
emphasizes that mine operators have a choice of which control method
they will use first. Under the final rule, they may use engineering
controls, administrative controls, or both; but if administrative
controls are utilized, a copy of such procedures must be posted and
given to each affected miner. The final rule affords mine operators
flexibility in selecting the most appropriate control method applicable
under the circumstances.
Although the final rule does not give preference to engineering
controls over administrative controls, engineering controls provide a
permanent method of modifying the noise source, the noise path, or the
environment of the miner exposed to the noise, thereby decreasing the
miner's exposure to harmful sound levels. Engineering controls do not
depend upon individual performance or human intervention to function.
Moreover, the effectiveness of engineering controls can be readily
determined using standardized acoustical measurement and assessment
procedures. In addition, routine maintenance ensures the long-term
effectiveness of engineering controls. Thus, MSHA has concluded that
the use of engineering controls provides the most consistent and
reliable protection to miners.
Administrative controls reduce exposure by limiting the amount of
time that a miner is exposed to noise through such actions as rotation
of miners to areas with lower sound levels, rescheduling of tasks, and
modifying work activities. MSHA believes that administrative controls
can be as effective as engineering controls and are typically less
costly than engineering controls, and MSHA anticipates growing interest
in implementation of administrative controls by the mining community.
MSHA will make guidance materials pertaining to administrative controls
available to the mining community before the effective date of the
final rule.
In the proposed preamble, MSHA had requested comment from the
mining community on the primacy of engineering and administrative
controls. The Agency received a number of comments from the public in
support of the primacy of engineering and administrative controls, as
well as a number of comments in support of equating personal hearing
protectors with controls. These comments are discussed below.
Commenters who favored permitting the use of hearing protectors to
meet the permissible exposure level asserted that hearing protectors
adequately protect the hearing of miners, are more cost effective, and
provide greater noise reduction than engineering controls. In addition,
some commenters believe that personal hearing protectors used in
conjunction with a hearing conservation program are as effective as
engineering and administrative controls.
Other commenters wanted MSHA to permit the use of hearing
protectors in lieu of engineering and administrative controls, provided
that the noise exposure did not exceed a TWA8 of 100 dBA.
These commenters stressed that this is allowed by OSHA's current
enforcement policy.
The OSHA noise standard at 29 CFR Sec. 1910.95 requires employers
to use engineering and administrative controls. Under the OSHA noise
standard, hearing protectors may be used only to supplement controls.
Current OSHA enforcement policy allows employers to rely on personal
protective equipment and a hearing conservation program rather than
engineering and/or administrative controls when hearing protectors will
effectively attenuate the noise to which the employee is exposed to
acceptable levels as specified in Tables G-16 or G-16a of the standard.
Furthermore, hearing protectors may not reliably be used when employee
exposure levels border on 100 dBA. MSHA's rulemaking record indicates
that a number of professional organizations have recommended that OSHA
rescind this policy and rely on engineering and administrative
controls.
As explained in the preamble discussion of Sec. 62.110 of the final
rule, MSHA has decided to adopt the approach of the proposal, which is
not to accept personal hearing protectors in lieu of engineering or
administrative controls. The Agency's position is supported by its own
research on noise reduction values of hearing protectors under actual
mining conditions. Additionally, this position is supported by studies
referenced in the preamble discussion of Sec. 62.110 that address noise
dose determination without adjustment for the use of hearing
protectors. Moreover, promulgating a rule which is consistent with OSHA
policy would result in a diminution of safety to miners in the metal
and nonmetal sectors of the mining industry. Section 101(a)(9) of the
Mine Act requires that no new standard reduce the protection afforded
miners by an existing standard. For metal and nonmetal mines, MSHA
currently requires the use of engineering or administrative controls to
the extent feasible to reduce exposures to the permissible exposure
level. Under existing standards if the permissible exposure level
cannot be achieved, hearing protectors must be made available to
miners. If OSHA's policy were to be adopted into the final rule, the
benefits of using feasible engineering and administrative controls
would be lost. In addition, OSHA's noise enforcement policy is based on
a judicial interpretation of ``feasible'' as used in the context of
OSHA's noise standard which is an established federal standard adopted
without rulemaking at the OSH Act's inception under Section 6(a) of the
OSH Act rather than the product of a regular OSHA rulemaking under
Section 6(b) of the OSH Act.
Under the Mine Act, one of the roles of the National Institute for
Occupational Safety and Health (NIOSH) is to advise MSHA in
establishing mandatory health and safety standards. While MSHA is aware
that NIOSH is seeking to develop an approach that would more accurately
adjust the noise reduction ratings of hearing protectors in actual
workplace use, the prospects for this remain uncertain. In addition,
adjustment methods that are appropriate for general industry may not be
appropriate in the mining environment. As explained in the preamble
discussion of Sec. 62.110 of the final rule, MSHA has found that
hearing protectors provide much less
[[Page 49598]]
noise reduction under actual mining conditions than was measured in the
laboratory. In many instances, noise reduction was minimal and highly
variable, indicating that hearing protector effectiveness cannot be
reliably predicted under actual use conditions.
During the rulemaking process, MSHA requested that NIOSH provide
its opinion on the hierarchy of noise controls. NIOSH stated in its
December 16, 1994, response (NIOSH, 1994) that there are three elements
in the hierarchy of effective noise controls:
(1) Preventing or containing workplace noise at its source;
(2) Removing the noise by modifying the pathway between the worker
and the noise source; and
(3) Controlling the worker's exposure by providing a barrier
between the worker and the noise source.
NIOSH further stated that noise controls must provide reliable,
consistent, and adequate levels of protection for each individual
worker throughout the life span of the controls, minimize dependence on
human intervention, consider all routes of entry (bone and air
conduction), and not exacerbate existing health or safety problems or
create additional problems of its own.
The conclusions of a report published by the Office of Technology
Assessment in 1985, entitled ``Preventing Illness and Injury in the
Workplace,'' also support MSHA's position. This report found that
health professionals rank engineering controls as the priority means of
controlling exposure, followed by administrative controls, with
personal protective equipment as a last resort.
In addition, Nilsson et al. (1977) studied hearing loss in
shipbuilding workers. The workers were divided into two groups. The
first group was exposed to sound levels of 94 dBA, with 95% of the
workers using hearing protectors. The second group was exposed to sound
levels of 88 dBA, with 90% of workers wearing hearing protectors. Both
groups were subjected to impulse noise up to 135 dB.
Despite the fact that the vast majority of the workers in both
groups wore hearing protectors, cases of noise-induced hearing loss
were common. As exposure durations increased, the amount of noise-
induced hearing loss increased, so workers exposed to sound at 94 dBA
exhibited more hearing loss than those exposed to 88 dBA. Slightly more
than fifty-eight percent of all of the workers had some degree of
hearing impairment, only 1.8% of which was caused by factors other than
noise. According to the researchers, the hearing protectors should have
reduced the noise by at least 13 dBA. They concluded that reliance on
hearing protectors alone is not sufficient to protect the hearing
sensitivity of the workers.
Although many commenters may prefer to use hearing protectors in
lieu of engineering or administrative controls to protect miners from
noise overexposures, MSHA has concluded that the scientific evidence
does not support this position, and that the approach taken in the
final rule best protects miners from further noise-induced hearing
loss.
A few commenters were concerned that the miner would suffer a loss
of pay if administrative controls were instituted and the miner was
rotated to a lower-paying job. However, the Mine Act does not authorize
the Secretary to require pay retention for miners rotated for the
purpose of reducing exposure to a harmful physical agent, and the final
rule does not adopt that comment.
Paragraph (a) of Sec. 62.130 of the final rule also adopts the
requirement of proposed Sec. 62.120(c)(1) that mine operators post on
the mine bulletin board the procedures for the administrative controls
in effect at the mine and provide all affected miners with a copy. MSHA
believes that miners must be specifically notified of the
administrative controls being used and actively follow them to achieve
effective results. Posting informs miners of critical work practices
necessary for reducing their noise exposures, especially when miners
are temporarily assigned to a different job. Moreover, this requirement
is consistent with section 109 of the Mine Act, which requires a mine
operator to have a bulletin board at the mine office or in an obvious
place near a mine entrance for posting of certain documents, including
notices required by MSHA regulations.
A number of commenters objected to a requirement for written
notification of miners of the administrative controls in use at the
mine. Some of these commenters were of the opinion that written
notification may not be the best method for alerting miners of
administrative control procedures, since these procedures may need to
be revised on a daily basis. Some commenters suggested that MSHA accept
informal workplace talks and safety meetings as compliance with the
written notification provision, which they believed would be burdensome
for mine operators.
MSHA has reviewed alternative methods for compliance under this
provision and has concluded that a notification provision with a narrow
application, such as in the final rule, appropriately informs miners of
critical measures to protect their hearing. Moreover, commenters are
encouraged to review the summary of the Regulatory Economic Analysis.
Most commenters requested that MSHA clarify the meaning of the term
``feasible.'' Many commenters specifically requested that MSHA include
economic considerations in the definition of feasibility. What
constitute ``feasible'' engineering and administrative noise controls
is discussed in Part VI of this preamble. As part of that discussion,
MSHA cites applicable case law, which specifically provides that a
consideration of feasibility must include both technological and
economic factors.
Some commenters suggested that ``feasible'' engineering controls
need to be capable of reducing a miner's noise exposure to the
permissible exposure level rather than to the lowest level achievable
for the control. Others suggested that a control should produce at
least a 3-dBA noise reduction before that control is considered
``feasible,'' which corresponds with MSHA's current policy. The
applicable case law on this issue provides that an engineering control
may be feasible even though it fails to reduce exposure to the
permissible level set by the standard, as long as there is a
significant reduction in exposure. As stated in the proposed preamble
and reiterated in the discussion of feasibility in this preamble, MSHA
considers a significant noise reduction to be a 3-dBA reduction in the
miner's noise exposure.
Several commenters were concerned about the development and
availability of engineering controls, including retrofit packages in
the marketplace. Engineering noise controls, including retrofit
equipment, are currently available for many types of mining machinery,
and many manufacturers sell noise control packages as options.
Furthermore, mining equipment manufacturers are diligently developing
new engineering controls to reduce exposure to noise. The preamble
discussion on feasibility includes a list of available controls for
commonly used mining equipment. Suggestions are also included in that
section for retrofitting existing mining equipment. MSHA is also
available to assist mine operators with obtaining retrofit packages and
other necessary controls for reducing noise sources.
Several commenters questioned whether the assumption that
engineering controls currently feasible in metal and nonmetal mines
could be adapted for use in coal mines. In fact,
[[Page 49599]]
MSHA's experience has been that many of the engineering noise controls
developed for machinery used in metal and nonmetal mines could be
easily used on the same types of machinery in coal mining, and vice
versa.
A few commenters requested that MSHA continue to ``grandfather''
older equipment, as the Agency does at metal and nonmetal mines.
Current metal and nonmetal enforcement policy allows a mine operator,
upon written request to the District Manager, up to 12 months to retire
a piece of machinery once it has been identified as the source of a
noise overexposure.
This comment has not been adopted in the final rule. Protection of
miners from the harmful effects of noise must be the first
consideration. The final rule does not take effect until 12 months
after the date of publication, which provides all mine operators with
adequate time to retire older, noisy equipment. After the final rule
takes effect no exceptions will be allowed for equipment that may be
nearing the end of its useful life.
One commenter stated that the final rule should not be technology-
forcing. However, Congress intended that MSHA health standards advance
technology in order to better protect miners' health. It is therefore
appropriate for MSHA to take into account, in determining feasibility,
the state-of-the-art engineering that exists in the mining industry at
the time the standard is promulgated.
A few commenters suggested that the final rule require mine
operators to develop a written plan for eliminating overexposures, so
that both miners and MSHA will be aware of the specifics of how a mine
operator intends to abate noise overexposures at a particular mine.
MSHA does not believe that requiring a written plan under the final
rule enhances health protection beyond that afforded by an action level
and implementation of all feasible controls. MSHA is also mindful of
its responsibilities under section 103(e) of the Mine Act, which
cautions the Agency not to impose an unreasonable burden on mine
operators, especially those operating small businesses, when requesting
information consistent with the underlying purposes of the Mine Act. It
should be noted, however, that Sec. 62.110(d) of the final rule
requires mine operators to notify a miner whose noise exposure equals
or exceeds the action level of the corrective action being taken to
address that exposure.
Paragraph (b) of Sec. 62.130 of the final rule, like proposed
Sec. 62.120(c)(2)(i), requires that if feasible engineering and
administrative controls fail to reduce a miner's exposure to the
permissible exposure level, the mine operator must continue to use the
controls to reduce the miner's exposure to as low a level as is
feasible.
Section 62.130(c) of the final rule adopts proposed Sec. 62.120(e)
and provides that at no time must a miner be exposed to sound levels
exceeding 115 dBA. Some commenters found the proposal somewhat
confusing, questioning whether there is a complete prohibition against
exposure to noise above 115 dBA or whether, under proposed Table 62-1
regarding reference durations, the rule permits a period of exposure to
noise above this level that is incorporated into a miner's dose
determination. MSHA intends the requirement of this paragraph to be
applied as has the existing prohibition in metal and nonmetal
regulations that no miner must be exposed to non-impulsive sound levels
exceeding 115 dBA. A clarifying notation has been added to Table 62-1
that at no time must any excursion exceed 115 dBA. To avoid confusion,
the term ``ceiling level,'' which was used in the proposal, has not
been adopted in the final rule. MSHA notes that OSHA's noise standard
does not use the term ``ceiling level.'' The preamble to OSHA's noise
standard further indicates that OSHA's ``* * * current standard does
not permit exposures above 115 dB, regardless of duration'' (46 FR
4078, 4132). In addition, to be consistent with exposure determinations
under Sec. 62.110(b)(2)(i), the final rule clarifies that exposure
determinations under this paragraph must be made without adjustment for
the use of any hearing protectors.
NIOSH's 1972 criteria document recommended a ceiling limit of 115
dBA. In its 1996 draft Criteria Document, NIOSH reaffirmed its
recommendation of a 115 dBA limit. Under this draft recommendation,
exposures to sound levels greater than 115 dBA would not be permitted
regardless of the duration of the exposure. NIOSH indicated that recent
research with animals indicates that the critical level is between 115
and 120 dBA. Below this critical level, the amount of hearing loss is
related to the intensity and duration of exposure; but above this
critical level, the amount of hearing loss is related only to
intensity. MSHA proposed the 115 dBA sound level limit based on these
recommendations, and also on the fact that MSHA's noise standard at
metal and nonmetal mines currently includes this limit.
Commenters took various positions on whether 115 dBA is the correct
level for maximum exposure. A number of commenters, however, believed
that the proposed prohibition of noise exposure above 115 dBA would be
too restrictive and unrealistic for the mining industry. Some of these
commenters suggested that occasional exposures above this level are
unavoidable when performing certain job tasks and that the level should
include a specified allowable time limit for these exposures, ranging
from 5 to 15 minutes. MSHA is not persuaded by these commenters'
concerns. In fact, the 115 dBA limit has been in effect at metal and
nonmetal mines for a number of years. Further, the potential damage to
miners' hearing when exposed to sound at such levels is so great that
it is not unreasonable to expect mine operators to take extra steps to
prevent miners' exposures.
It must be emphasized that this provision prohibits exposures above
115 dBA for any duration, not as a time-weighted average. This means
that Table 62-1, which includes reference durations of noise exposures
at various sound levels, should not be read as allowing excursions
above 115 dBA, even though the average over a quarter of an hour would
not exceed 115 dBA. However, it should also be noted that MSHA intends
to apply this prohibition as it has enforced the same limit under the
metal and nonmetal standard. This means that miners may not be exposed
to sound levels exceeding 115 dBA as measured using A-weighting and
slow response. As a practical matter, there may be some exposure to
sound above this level which is of such limited duration that it cannot
be measured. Obviously, compliance and enforcement are affected by the
limitations of the instrumentation used to measure sound.
Some commenters stated that older mining machinery as well as
equipment such as pneumatic tools, jackleg drills, welding machines,
and relief valves typically exceed the 115 dBA limit. MSHA is aware
that there are noise sources in the mining industry, which may also
include unmuffled pneumatic rock drills and hand-held channel burners,
that produce sound levels which exceed 115 dBA. However, based on
MSHA's experience, practically all of these noise sources can be
managed with engineering controls and kept below the sound level of 115
dBA. For example, there is a muffler available for the jackleg drill,
and burner tips are available for the hand-held channel burner, that in
many cases will lower the sound level to below 115 dBA. Sound from
other pneumatic tools can also be muffled.
In addition, mine operators should be aware that significant noise
reductions
[[Page 49600]]
can be achieved by using alternative equipment, such as the diamond
wire saw and water jet, instead of a hand-held channel burner. In the
coal mining sector, for example, roof bolting machines have replaced
stopers, which are hand-held pneumatic roof drills. The roof bolting
machines produce much less noise than the stoper.
Some commenters requested that MSHA permit exposures to exceed 115
dBA when the noise source is a warning signal or an alarm. The Agency
does not intend that the 115 dBA sound level limit apply to warning
signals or alarms; the ability to hear these signals is critical to the
safety of miners. However, alarm and warning signal sound levels must
be integrated into the overall noise exposure of miners.
Several commenters objected to enforcing a ceiling level with
personal noise dosimeters. They believed that shouting, bumping the
microphone, or whistling could give false readings which may be
interpreted as exceeding the 115-dBA level. As a practical matter, the
fact that the indicator on a personal noise dosimeter shows that the
115-dBA sound level was exceeded does not mean that MSHA will take
enforcement action. Rather, the duration of the sound level would need
to be sufficient for it to exceed 115 dBA when measured using the slow
response on a sound level meter, or on an equivalent type of
instrument. This measurement procedure should also serve to eliminate
concerns that impulse/impact noise would exceed the 115 dBA limit and
result in a citation.
In the preamble to the proposed rule, MSHA requested comments on
whether there should be an absolute dose ceiling, regardless of the
economic feasibility of control by an individual mine operator. One
commenter stated that it would be inappropriate to include a maximum
dose ceiling in the final rule without taking feasibility
considerations into account. As a result of the lack of scientific
consensus on this issue, MSHA has determined that a separate provision
for a dose ceiling is unnecessary. The 115-dBA sound level limit, in
conjunction with the requirement for dual hearing protectors at a
TWA8 of 105 dBA in Sec. 62.140 of the final rule, adequately
protects the hearing sensitivity of miners.
The final rule, like the proposal, does not include a separate
provision for impact or impulse noise. Presently, there is insufficient
scientific data to support such a standard. MSHA is unaware of any
effective sampling methodology for identifying and measuring sound at
this level. Since industrial impulse and impact noise are almost always
superimposed on a background of moderate-to-high levels of continuous
noise, and since both types of noise may be harmful, MSHA believes that
it is only reasonable to consider their effect together, rather than to
treat each separately. Accordingly, under the final rule all sounds
from 90 dBA to at least 140 dBA are to be included in the range of
integration. Impact or impulse noise is therefore considered with
continuous noise when determining a miner's noise exposure level.
Section 62.140 Dual Hearing Protection Level
This section of the final rule establishes requirements for the use
of dual hearing protection. Included in this section is the requirement
that the mine operator must provide and ensure that both an earplug-and
an earmuff-type hearing protector are used simultaneously when a
miner's noise exposure exceeds the dual hearing protection level of a
TWA8 of 105 dBA, or equivalently, a dose of 800% of that
permitted by the standard during any work shift.
Two features of the final rule are slightly different from
Sec. 62.120(d) of the proposal. First, explicit language has been added
that the dual hearing protector requirement is in addition to the
actions required for noise exposure that exceed the permissible
exposure level. The preamble discussion of proposed Sec. 62.120(d)
reflected this intent. This language has been added to Sec. 62.140 of
the final rule for the purpose of clarifying the requirements of this
section, which are set forth separately from the section on the
permissible exposure level.
In addition, the final rule also includes the range of sound
levels, from 90 dBA to at least 140 dBA, which must be integrated in
determining a miner's exposure under this section. The range is
included in the definition of ``dual hearing protection level'' in
final Sec. 62.101. MSHA had proposed that a miner's noise exposure
measurement integrate all sound levels between 80 dBA to at least 130
dBA during the miner's full work shift. MSHA decided, however, not to
lower the range of integrated sound levels for a miner's dose
determination under Sec. 62.130 of the final rule regarding the
permissible exposure level (see discussion of Sec. 62.130). The dual
hearing protection requirement of Sec. 62.140 is directly related to
Sec. 62.130, in that it requires dual hearing protection in addition to
engineering and administrative controls. A more detailed explanation of
the range of integration is provided in the preamble discussion on
Sec. 62.110(b)(2)(ii), regarding noise exposure assessment.
The proposed dual hearing protection requirement generated many
comments. The proposal was favored by some commenters, and a few who
favored the use of dual hearing protection also suggested that MSHA
reduce the dual hearing protection level to 100 dBA. Most commenters
who opposed the proposal suggested that a single hearing protector with
a sufficient noise reduction rating can attenuate sound levels and
reduce miner exposures below the permissible exposure level. One
commenter believed that MSHA should replace the proposal with
performance-oriented language which would require the use of
``adequate'' hearing protection. Also, one commenter questioned the
adequacy of the scientific studies upon which MSHA based the proposed
requirement.
MSHA is adopting the proposed dual hearing protection requirement
because the scientific evidence shows that the additional noise
reduction that is gained by the use of dual hearing protection will
protect the hearing sensitivity of miners who are exposed to high sound
levels. In addition, the scientific evidence supports MSHA's conviction
that a TWA8 of 105 dBA (800%) is an appropriate level above
which dual hearing protection should be required, since this level of
noise exposure can quickly damage the hearing sensitivity of the
exposed miner. MSHA is also relying upon the research which shows that
a single hearing protector may not adequately protect workers whose
noise exposures exceed a TWA8 105 dBA.
The research discussed in the preamble to the proposal (Berger,
1984; Berger, 1986; and Nixon and Berger, 1991) shows that dual hearing
protectors provide significantly greater protection than a single
hearing protector and is effective for protecting workers above a
TWA8 of 105 dBA.
For example, Berger, in EARLOG 13 (1984), has shown that the use of
dual hearing protectors provides greater noise reduction, on the order
of at least 5 dB greater than the reduction of either hearing protector
alone. Berger recommends dual hearing protectors whenever the
TWA8 exceeds 105 dBA. In addition, Nixon and Berger (1991)
report that earplugs worn in combination with earmuffs or helmets
typically provided more attenuation than either hearing protector
alone.
The use of dual hearing protection is also required by the U.S.
armed services when workers are exposed to high sound levels.
Additionally, MSHA's policy under the existing standards for
[[Page 49601]]
coal, metal, and nonmetal sectors requires the use of dual hearing
protectors whenever the noise reduction of a single hearing protector
does not reduce the miner's noise exposure to within the permissible
exposure level. Current metal and nonmetal policy indicates the need to
consider dual hearing protection specifically at sound levels exceeding
105 dBA where hand-held percussive drills are used. Also, dual hearing
protection is recommended by policy where hand-held channel burners and
jumbo drills are used, but no sound level is specified at which such
protection should be used.
Regarding the commenters who supported the requirement for dual
hearing protection, but requested that MSHA reduce the dual hearing
protection level to a TWA8 of 100 dBA, the Agency does not
believe that there is adequate scientific evidence to support lowering
the proposed level. Rather, the Agency is relying upon the scientific
studies noted above which recommend dual hearing protectors whenever
the TWA8 exceeds 105 dBA.
With respect to the use of canal cap-type hearing protectors under
this paragraph of the final rule, MSHA notes that it considers a canal
cap-type hearing protector to be neither an earplug-type or earmuff-
type hearing protector. A canal cap hearing protector is an acceptable
single-type hearing protector but cannot be combined with either a
plug-type or muff-type protector, because a proper seal or fit cannot
be achieved. Therefore, the Agency intends that a canal cap-type
hearing protector may not be used for compliance with the dual hearing
protector requirements of this paragraph.
Several commenters believed that the proposed dual hearing
protection requirement created a safety hazard because the hearing
protectors would prevent a miner from hearing warning signals, audible
alarms, verbal communication, and roof talk. MSHA believes that the use
of dual hearing protectors would not create an additional safety hazard
because the high sound levels generated by some mining equipment will
interfere with the detection of roof talk, verbal communications, and
audible alarms. In fact, research by Prout, 1973, discussed under
Sec. 62.160 of the preamble, shows that the noise emitted by mining
equipment operating in close proximity to a miner's assigned work area
masks roof talk. Moreover, if hearing protectors are not worn, a
temporary threshold shift will impair a miner's ability to hear roof
talk, verbal communications, or warning signals when the mining
equipment ceases to operate. Because the use of dual hearing protectors
will minimize the extent of any temporary threshold shift experienced
during exposure to high sound levels, MSHA expects that the dual
hearing protection will be used in high sound level environments and
removed in quiet environments. This procedure would enhance safety.
A few commenters who opposed the proposal for dual hearing
protection were concerned that the use of earmuffs may interfere with
the use of other personal protective equipment such as hard hats,
safety glasses, and welding shields. MSHA believes that the proper
selection and combination of hearing protectors should alleviate this
concern. For example, newer models of ear muffs, which are readily
available, are specifically designed to be used with hard hats. Other
models which were specifically designed for use with safety glasses or
welding shields are also readily available.
In response to the commenter who expressed a concern regarding
compliance with this section under the circumstances where a medical
condition would preclude the use of a hearing protector, MSHA notes
that the dual hearing protection requirement of this section must be
provided in accordance with Sec. 62.160. Section 62.160(a)(5) allows
the miner to choose a different hearing protector if wearing the
selected hearing protectors is subsequently precluded due to a medical
pathology of the ear.
Section 62.150 Hearing Conservation Program
Under the proposed rule, the individual elements of a hearing
conservation program were located in several separate sections.
``Hearing conservation program'' was defined in Sec. 62.110 of the
proposal as a ``generic reference'' to the requirements in proposed
Secs. 62.140 through 62.190, which addressed audiometric testing
requirements and miner notification and reporting requirements.
In the interest of clarity and in response to commenters, this
section consolidates the elements of a hearing conservation program in
one location in the final rule, rendering a definition of ``hearing
conservation program'' unnecessary, and the proposed definition has
therefore not been adopted in the final rule. In addition to the
elements referenced in the proposed definition of ``hearing
conservation program,'' this section also includes as program elements
a system of monitoring under Sec. 62.110, the use of hearing protectors
under Sec. 62.160, miner training under Sec. 62.180, and recordkeeping
under Sec. 62.190. This new section is consistent with OSHA's
definition of a hearing conservation program.
MSHA received a number of general comments on specific elements
that commenters believed should be included in any hearing conservation
program. MSHA also received many comments on specific requirements that
were proposed for each of those elements, such as appropriate
audiometric test procedures and the use and maintenance of hearing
protectors. Comments addressing the elements that should be included in
a hearing conservation program are discussed under this section of the
preamble. Comments which address the specific requirements for each
program element are discussed under the section where the specific
requirements are located. For example, a comment that addresses the
role of hearing protectors in a hearing conservation program is
discussed here, while a comment dealing with fitting of hearing
protectors is discussed in the preamble under Sec. 62.160.
None of the commenters supported MSHA's proposed definition of
``hearing conservation program.'' Some commenters pointed out that the
proposed definition constituted an audiometric testing program only,
not a hearing conservation program. These commenters recommended that
the use of hearing protectors should also be included. A number of
commenters recommended that MSHA adopt the traditional definition of a
hearing conservation program used by OSHA, stating that any other
definition would be confusing. These commenters stated that the term
``hearing conservation program'' has been used in general industry
since the 1970's to refer to a comprehensive package of actions,
including noise exposure monitoring, noise controls, hearing evaluation
and protection, training, and recordkeeping.
MSHA agrees with the commenters who believed that the proposed
definition of ``hearing conservation program'' was too narrow and that
adoption of a definition that was similar in scope to OSHA's would
avoid unnecessary confusion. Accordingly, the elements identified for
inclusion in a hearing conservation program under this section of the
final rule are, with one exception, consistent with OSHA's definition
of ``hearing conservation program.''
Like OSHA's noise standard, MSHA's final rule does not include the
use of engineering and administrative controls as an element of a
hearing conservation
[[Page 49602]]
program. However, Sec. 62.130 of the final rule requires the
implementation of all feasible engineering and administrative noise
controls whenever a miner's noise exposure exceeds the permissible
exposure level. Therefore, although a ``hearing conservation program''
under the final rule does not specifically include the use of
engineering and administrative controls, the application of such
controls is required to remedy miner overexposure. MSHA regards an
effective hearing conservation program as a supplement to the first
line of defense against noise overexposures, which is the
implementation of all feasible engineering and administrative noise
controls.
This section of the final rule provides that, when a miner's noise
exposure equals or exceeds the action level of TWA8 of 85
dBA, the mine operator must promptly enroll the miner in a hearing
conservation program. This requirement is derived in part from proposed
requirements in Sec. 62.120(b)(2) and (c)(1), which would have provided
for a miner's enrollment in a hearing conservation program if the
miner's noise exposure exceeded either the action level or the
permissible exposure level. Proposed Sec. 62.120 would also have
required miner training, hearing protector use, and a system of
monitoring, but did not specifically designate those items as elements
of a hearing conservation program, as does the final rule.
Paragraphs (a) through (e) of Sec. 62.150 of the final rule
enumerate the elements of a hearing conservation program, which include
a system of monitoring, the use of hearing protectors, audiometric
testing, training, and recordkeeping. Each paragraph also refers to the
specific section of the final rule where the detailed requirements of
each program element are located.
Paragraph (a) of Sec. 62.150 of the final rule requires that the
hearing conservation program include a system of monitoring in
accordance with Sec. 62.110, which provides that the system of
monitoring must evaluate each miner's noise exposure sufficiently to
determine continuing compliance with the requirements of part 62. This
requirement is derived from proposed Sec. 62.120(f), which would have
required a system of monitoring, but which did not include monitoring
as an element of the hearing conservation program. A more detailed
discussion of exposure monitoring is included in the preamble under
Sec. 62.110.
Paragraph (b) of Sec. 62.150 of the final rule includes the use of
hearing protectors, in accordance with Sec. 62.160, as an element of
the hearing conservation program. This requirement is derived from
proposed Sec. 62.120(b)(3). A detailed discussion of hearing protectors
is found under Sec. 62.160 of the preamble.
Paragraph (c) of Sec. 62.150 of the final rule includes audiometric
testing, in accordance with Secs. 62.170 through 62.175 of the final
rule, as a hearing conservation program element. As discussed above,
audiometric testing would have been included as a program element under
the proposal, and has been adopted as an element in the final rule.
Detailed discussion of audiometric testing, test procedures, evaluation
of audiograms, and other related issues can be found in the preamble
under Secs. 62.170 through 62.175.
Paragraph (d) of Sec. 62.150 of the final rule includes miner
training, to be conducted in accordance with Sec. 62.180 of the final
rule, as an element of the hearing conservation program. Under
Sec. 62.120(b)(1) of the proposal, training would have been required
for miners whose exposure exceeded the action level, but the proposed
rule would not have included training as a hearing conservation program
element. Extensive discussion of miner training under the final rule
can be found in the preamble under Sec. 62.180.
Finally, paragraph (e) of Sec. 62.150 of the final rule provides
that the hearing conservation program must include recordkeeping in
accordance with Sec. 62.190 of the final rule. Issues related to access
to records, maintenance, and retention are discussed in detail in the
preamble under Sec. 62.190.
Section 62.160 Hearing Protectors
Section 62.160 specifies the requirements for hearing protectors.
The final rule is essentially identical to proposed Sec. 62.125 with a
few minor changes. Proposed Sec. 62.125 required that miners have a
choice of one plug-type and one muff-type hearing protector. Under
Sec. 62.160(a)(2) of the final rule, miners must be allowed to choose
from at least two of each type. In the event that, under Sec. 62.140,
dual hearing protection is required, miners must be allowed to choose
one of each type from the selection offered under Sec. 62.160(a)(2).
Under Secs. 62.120 and 62.125 of the proposal, mine operators would
have been required to ensure that miners wore hearing protection in
specific circumstances: when a miner's exposure exceeded the
permissible exposure level; or when a miner's exposure exceeded the
action level and the miner was determined to have a standard threshold
shift or would have to wait 6 months before a baseline audiogram. The
hearing protectors would have been required to be worn at any sound
level between 80 and 130 dBA. In its place, Sec. 62.160(b) of the final
rule specifies that mine operators must ensure that miners wear hearing
protectors under similar circumstances. Under the final rule the mine
operator must ensure that hearing protectors are worn by miners
whenever their noise exposure exceeds the permissible exposure level,
either until feasible engineering and administrative controls have been
implemented, or despite the use of all feasible engineering and
administrative controls. Additionally, mine operators must ensure that
a miner whose exposure equals or exceeds the action level wears hearing
protectors, either if the miner has experienced a standard threshold
shift or more than 6 months will pass before a baseline audiogram can
be conducted. The final rule, however, does not adopt the provision
proposed at Sec. 62.125(b) that in those cases where hearing protectors
are required to be worn, the mine operator must ensure that the
protector is worn by the miner when exposed to sound levels required to
be integrated into a miner's noise exposure measurement.
The final rule adopts the proposed provisions that the hearing
protector is to be fitted and maintained in accordance with the
manufacturer's instructions; that hearing protectors and necessary
replacements are to be provided by the mine operator at no cost to the
miner; a miner whose hearing protector causes or aggravates a medical
pathology of the ear must be allowed to select a different hearing
protector from among those offered.
Selection of Hearing Protectors
MSHA's existing noise standards require mine operators to provide
adequate hearing protectors but do not specify that a variety of
hearing protectors be offered. OSHA's noise standard requires that
employees be allowed to select from a variety of suitable hearing
protectors provided by the employer but does not define variety. OSHA
states in the 1981 preamble to its noise standard that ``[T]he company
must make a concerted effort to find the right protector for each
worker-one that offers the appropriate amount of attenuation, is
accepted in terms of comfort, and is used by the employee.''
MSHA considered several studies and comments before concluding that
the minimum selection appropriate for miners consists of at least two
types of earmuffs and two types of earplugs that would provide adequate
noise reduction.
[[Page 49603]]
The National Hearing Conservation Association's Task Force on
Hearing Protector Effectiveness (Royster, 1995) recommends that
employers consider numerous criteria when selecting the variety of
hearing protectors to be made available to their workers. According to
the Task Force, the most important criterion for choosing a hearing
protector is ``the ability of a wearer to achieve a comfortable noise-
blocking seal which can be maintained during all noise exposures.''
Other criteria include the hearing protector's reduction of noise, the
wearer's daily noise exposure, variations in sound level during a work
shift, user preference, communication needs, hearing sensitivity of the
wearer, compatibility with other safety equipment, the wearer's
physical limitations, climate, and working conditions.
Berger (1986) stresses the importance of comfort, arguing that if a
miner will not wear a highly rated but uncomfortable hearing protector,
its actual effectiveness is greatly reduced (or nonexistent).
Conversely, the miner may wear a comfortable but less effective hearing
protector consistently, thereby gaining greater effective protection.
Berger (1981) also recommends that an employee should have two weeks to
try out an adequate hearing protector and select another one if the
original selection does not perform satisfactorily.
MSHA believes that such a trial period further encourages miners'
acceptance of the use of hearing protectors and may be necessary for
miners to determine if the hearing protectors they have selected are
comfortable and appropriate for prolonged periods of use. If
significant discomfort occurs, MSHA encourages the mine operator to
allow the affected miner to select an alternate hearing protector. In
any case, provision of an alternative hearing protector is mandatory
under the final rule if required by a medical condition or because the
miner has experienced a standard threshold shift.
Mine conditions such as dust, temperature, and humidity can cause
one type of hearing protector to be more comfortable than another. For
example, even under normal mining conditions, some miners may
experience problems with earmuffs because of a buildup of perspiration
under the seals. The report Communication in Noisy Environments
(Coleman et al., 1984) finds earmuffs to be better suited to mining
conditions than earplugs, because helmet-mounted earmuffs are
comfortable, easy to fit and remove, effective, and hygienic. However,
compressible foam earplugs interfere less with communication and
awareness of surroundings than do earmuffs, and may be more comfortable
in hot, humid conditions.
Comfort alone does not determine a miner's choice of hearing
protector. Coleman et al. (1984) state that other factors, such as:
* * * concern with hygiene, belief in (real or presumed)
communication difficulties, and social constraints * * * can
influence the extent to which workers will use the protection
provided * * * Sweetland (1981) found concern about communication
difficulties to be a major factor in mine workers' acceptance of
protectors.
One commenter suggested that because earmuffs might not provide
adequate noise reduction, mine operators should be allowed to require
specific hearing protectors to ensure that their employees receive the
best protection. MSHA agrees that employees should receive the best
available protection.
Accordingly, the final rule does not prevent mine operators from
selecting among the wide variety of styles, types, and noise-reduction
ratings available in hearing protectors which would afford miners the
best protection available. Moreover, MSHA maintains that the
requirement that mine operators encourage the safe and effective use of
hearing protectors gives them incentive to provide an appropriate
variety of types. MSHA further maintains that if miners are allowed to
choose from a selection of hearing protectors, particularly if given
appropriate training, as required under this rule, they will be more
likely to wear and maintain their hearing protectors for optimal noise
reduction.
The comment that ``miners will only wear plugs that are
comfortable'' represents the consensus view, and a number of comments
to the proposed rule noted that a choice from at least one of each type
is inadequate. On the basis of comments reviewed and the international
consensus (including the U. S. armed services) that workers should
choose from a selection of several hearing protectors, MSHA has
concluded that the use of hearing protectors will be better accepted by
miners if they have the opportunity to choose appropriate hearing
protectors from an expanded, but not unlimited, selection. Thus, the
final rule requires that at least two plug-type and two muff-type
protectors be offered to miners.
Hearing Protectors for Miners With Significant Hearing Loss
Hearing loss due to noise and aging both affect the ear at higher
sound frequencies, and most earplugs and earmuffs are more effective at
reducing sounds of higher than lower frequencies. As a result, a miner
with significant hearing loss who is wearing a normal hearing protector
would experience even further reduction in hearing at the higher
frequencies. In this situation, the miner could run the risk of not
hearing or comprehending otherwise audible warnings.
Pfeiffer (1992) supports this reasoning, suggesting that greater
care be exercised when selecting hearing protectors for workers
experiencing hearing loss. He notes that it is important not to
overprotect workers, because if workers experience difficulty in
communicating, they will be reluctant to wear hearing protectors.
An alternative is the communication-type hearing protector, which
combines an earmuff with a radio receiver so that the wearer can hear
important conversations or warnings. Although no comments were received
on the use of communication-type hearing protection devices for hearing
impaired miners, MSHA cautions mine operators against their use in very
high noise areas because the sound level transmitted into the ear cup
may be hazardous. Some manufacturers of communication-type hearing
protectors, however, have placed limiters in the electronics to prevent
potentially hazardous sound levels being transmitted.
Even though some researchers have indicated that using a hearing
protector may cause communication problems for a hearing impaired
miner, MSHA has determined not to require special hearing protectors
and not to limit the choices of hearing protectors for the hearing
impaired. As a result, the rule allows mine operators the maximum
flexibility in addressing this matter in ways appropriate to local
conditions and individual needs.
Use of Hearing Protectors Above 80 dBA
Under Sec. 62.125(b) of the proposal, the use of hearing protectors
would have been required when the sound levels exceed those which were
proposed to be integrated into the noise exposure measurement. This
requirement has not been adopted in the final rule. This provision,
while intended to require the use of hearing protectors above 80 dBA
when the miner's exposure exceeded the permissible exposure level,
would in effect have required hearing protector usage above 80 dBA, and
some commenters to the proposed rule were concerned that this would
result in all miners having to wear hearing protectors throughout every
shift. A number of commenters who objected to
[[Page 49604]]
the proposal noted that miners should be permitted to remove hearing
protectors when the sound level falls below 80 dBA, and that MSHA
should recommend wearing hearing protectors above 85 dBA and require
them above 90 dBA. One commenter noted that it is impossible to enforce
the use of hearing protectors based on the sound level unless there is
a practical means of knowing what the sound level is at all times, in
order to know when it exceeds the threshold level.
MSHA agrees with the commenters who pointed out that the provision
in the proposal would have required hearing protector usage above 80
dBA, which would have resulted in miners having to wear hearing
protectors throughout every shift. MSHA did not intend for the use of
hearing protectors to be based on the threshold level, thus the
proposed provision has not been adopted. The final rule does set forth
specific circumstances under which mine operators must ensure that
miners use hearing protectors: when the miner's noise exposure exceeds
the permissible exposure level, until engineering and administrative
controls have been implemented, or despite the use of such controls;
and when the miner's exposure is at or above the action level, and the
miner has incurred a standard threshold shift, or more than 6 months
will pass before the miner's baseline audiogram can be conducted.
Use of hearing protectors is not based on the threshold levels.
MSHA has determined that it is the responsibility of the mine operator
to determine when beyond the specific requirements of the final rule
hearing protectors should be worn. This is one goal of the mine
operator's monitoring program.
Fitting of Hearing Protectors
Section 62.160(a)(3) of the final rule addresses the fitting of
hearing protectors, and is identical to Sec. 62.125(c) of the proposed
rule. The final rule requires that mine operators ensure that hearing
protectors be fitted in accordance with manufacturer's instructions.
Many commenters supported the requirement that hearing protectors
be properly fitted. A number of commenters observed that earplugs vary
more from laboratory data than earmuffs because earplugs are harder to
fit properly. Several commented that proper fit depends upon the
wearer's ear canal size and shape, manual dexterity, and motivation.
Others stated that people often select a comfortable earplug that does
not effectively seal the ear canal, so that it provides little
protection. MSHA recognizes a lack of consensus on fitting procedures
but notes that research demonstrates that proper fitting can increase
the effectiveness of hearing protectors.
For example, Chung et al. (1983) report that the major factor in
the performance of earmuffs is the fit, which is dependent on headband
tension. They report that, while adequate tension is necessary for
effective noise reduction, high headband tension also generally causes
discomfort. Chung et al. concluded that proper fitting can increase the
effectiveness of earmuffs.
MSHA considered the use of audiometric data base analysis the long-
term collection of audiograms to determine the effectiveness of hearing
protectors and concluded that audiometric data base analysis is
inappropriate for determining fit because it does not provide immediate
feedback on individual fit. Audiometric data base analysis requires
multiple subjects, and is useful for determining the adequacy of the
hearing conservation program (protecting the hearing sensitivity of a
group of workers) but not the adequacy in protecting an individual.
Furthermore, audiometric data base analysis requires audiograms to be
conducted on an annual basis. If no interim protection is provided
between audiograms, a miner's hearing sensitivity could be irreversibly
damaged.
As stated in the preamble to the proposal, MSHA agrees that proper
fitting is necessary to ensure optimal effectiveness of hearing
protectors and that it should not be left solely up to the individual
miner to determine if the hearing protector fits properly.
Some commenters saw the need for an accurate, reliable, and
inexpensive method of testing the fit of earplugs and earmuffs. MSHA
agrees that such a fit test for earplugs and earmuffs is needed in
order to determine the amount of protection an individual obtains from
a hearing protector, but none exists at this time. MSHA believes that,
until such a test is developed, the manufacturer's instructions should
be used to fit earmuffs and earplugs.
Some commenters noted that not all manufacturers' instructions are
adequate to ensure proper fit. In addition, one commenter was opposed
to mandating the manufacturers' instructions, claiming that doing so
was an unlawful delegation of MSHA's responsibility. MSHA disagrees.
There are many instances of regulations requiring that manufacturers'
instructions be followed, because the manufacturer of the instrument,
machine, or protective device is the most knowledgeable of the
features, performance, and use of the device. For example, the safety
standards for explosives at metal and nonmetal mines require that
initiation systems be used in accordance with the manufacturer's
instructions. Therefore, in light of the wide variety of hearing
protectors available, the broad range of subjective fitting procedures,
and the lack of consensus on an objective fitting method, MSHA has
concluded that the manufacturers' instructions provide the best model
for fit at this time.
One commenter noted that the best fit is obtained when
individualized training is available to the user. MSHA agrees that
training is a key element in the fitting of hearing protectors, as
reflected in the final rule (see Sec. 62.180).
Maintenance of Hearing Protectors
Section 62.160(a)(3) of the final rule requires that mine operators
ensure that a hearing protector is maintained in accordance with the
manufacturer's instructions. Many manufacturers recommend soap, warm
water, and careful rinsing to clean the hearing protector.
Manufacturers also discourage solvents and disinfectants as cleaning
agents because they can cause skin irritation and some can damage the
hearing protector. In most cases, the proper insertion technique for
earplugs includes proper basic hygiene cleaning the hands before
rolling or inserting earplugs.
MSHA reviewed standards of hearing protector maintenance among the
U.S. armed forces and the international community. The consensus of the
standards was that damaged or deteriorated hearing protectors must be
replaced. Research also demonstrates that non-disposable hearing
protectors should be replaced between 2 and 12 times per year (Berger,
1980). Constant wear causes hearing protectors to lose their
effectiveness. For example, headbands on earmuffs can lose their
compression ability; the soft seals surrounding the ear cup on earmuffs
can become inflexible; and plastic earplugs can develop cracks, shrink,
or lose their elasticity. All types are susceptible to contamination.
MSHA recognizes that it is difficult to keep hearing protectors
clean in the mining environment. Using contaminated hearing protectors,
however, may contribute to a medical pathology of the ear. Once the
skin has been abraded or inflamed, microorganisms in the ear or on a
hearing protector can invade the skin. When hearing protectors appear
to be the cause of inflammation of the external ear canal (otitis
externa), the
[[Page 49605]]
hearing protector is often found to be contaminated with an irritating
or abrasive substance. This situation can be corrected with proper
cleaning of the hearing protector before use.
As noted in the proposed rule, miners have been known to alter
hearing protectors to make them more comfortable. Such alterations have
included cutting off the ends of earplugs or stretching out the head-
band on earmuffs to decrease the tension. These alterations can
significantly decrease the hearing protector's effectiveness. In
addition, hearing protectors can be damaged from exposure to heat,
cold, ozone, chemicals, or dirt. Because such conditions are common in
the mining industry, hearing protectors must be periodically checked
and replaced if damage is found. While MSHA recognizes that it is
difficult to keep hearing protectors clean and undamaged in the mining
environment, the final rule requires mine operators to ensure that
hearing protectors are maintained in accordance with manufacturers'
instructions.
Replacement of Hearing Protectors
Section 62.160(a)(4) of the final rule is identical to proposed
Sec. 62.125(d). This section requires the mine operator to provide the
hearing protector and necessary replacements at no cost to the miner.
MSHA intends for this section to include repairs to a miner's hearing
protector when it becomes damaged or deteriorated to the point that the
required protection is compromised. Commenters agreed that this should
be the case.
Replacement of hearing protectors would take place according to the
manufacturer's instructions upon finding any deterioration that could
adversely affect the hearing protector's effectiveness or upon
diagnosis of a medical pathology caused or aggravated by the hearing
protector provided (see following section for discussion of medical
pathology). For example, manufacturers of disposable earplugs may state
in their instructions that the earplugs should be replaced after each
use.
Replacement Due to Medical Pathology
Section 62.160(a)(5) of the final rule is identical to proposed
Sec. 62.125(e). This section requires the mine operator to provide an
individual miner with a different, more appropriate, type of hearing
protector when presented with evidence of a medical pathology (for
example, otitis externa or contact dermatitis). The definition of
``medical pathology'' is intended to cover injuries. If, for example, a
miner suffered a burn in the ear canal and could no longer use the
earplugs he or she had earlier selected, he or she must be allowed to
select an earmuff. Comments to the proposed rule indicated a consensus
that miners should be permitted to change their choice of hearing
protector on the basis of the opinion of a medical professional. A
preliminary diagnosis of medical pathology by a family physician or
nurse must be accepted by a mine operator for the purposes of this
requirement.
One commenter stated that people wearing hearing protectors are
prone to ear infections. Berger (1985), however, reports that although
there are some preexisting ear canal conditions and environmental
conditions that prevent the use of certain hearing protectors, in
general, otitis externa occurs in approximately 2% of both users and
nonusers of hearing protectors. He therefore concludes that regular
wear of hearing protectors does not increase a person's chances of
contracting otitis externa. In any case, disposable hearing protectors
may be warranted for individuals prone to infections.
MSHA's existing noise standards do not specifically address the
replacement of hearing protectors. OSHA's noise standard simply
requires that hearing protectors be replaced as necessary. Based upon
the research and several international standards, MSHA believes that
hearing protectors need to be replaced whenever a medical pathology is
present. Such replacements must also be available at no cost to the
miner.
Circumstances Requiring the Use of Hearing Protection
Section 62.160(b) of the final rule sets forth the circumstances in
which mine operators must ensure that hearing protectors are worn.
Section 62.160(b) incorporates requirements of proposed
Secs. 62.125(b)(2) and 62.125(c)(2)(iii). Section 62.160(b) requires
that mine operators ensure the use of hearing protectors when the
miner's exposure exceeds the permissible exposure level before the
implementation of all feasible engineering and administrative controls,
or if the miner's exposure continues to exceed the permissible level
despite the use of all feasible controls. Sections 62.160(c)(1) and
(c)(2) require that mine operators ensure the use of hearing protectors
when the miner's noise exposure is at or above the action level and the
miner has experienced a standard threshold shift or it takes more than
6 months to conduct the baseline audiogram.
The proposal's requirement that the mine operator ensure the use of
hearing protectors under particular circumstances generated comments
concerning convenience, comfort, and noise reduction. One commenter to
the proposed rule noted that to meet the proposed requirement, miners
would need to wear hearing protectors throughout entire shifts, which
would be very inconvenient.
Some research supports the assumption that miners would resist
wearing hearing protectors as prescribed. Despite mandatory use of
hearing protectors, most workers in the Abel (1986) study admitted to
wearing their hearing protectors less than 50% of the time. Further,
many modified their hearing protectors to provide greater comfort. Many
of the modifications lowered the effectiveness of the hearing
protectors.
As noted by Berger (1981), persons with medical pathologies of the
ear are more likely than others to resist wearing hearing protectors
because of pain or extreme discomfort associated with their use. Berger
suggests that persons who are more prone to otitis externa would need
to be monitored more closely for failure to wear their hearing
protectors.
As many have emphasized, hearing protectors are only effective if
they are worn. Their effectiveness is diminished if they are not worn
for the duration of any exposure. Chart NR1, below, illustrates that
the amount of noise reduction provided is directly dependent upon the
proportion of exposed time during which the hearing protector is worn.
For example, if a hearing protector with a noise reduction rating
(NRR) of 29 dB is worn during only half the exposure time, the wearer
will effectively obtain only about 5 dB of noise reduction. A noise
reduction rating of 29 dB is among the highest reported by hearing
protector manufacturers; yet, if a hearing protector with this rating
is not worn 100% of the time that the wearer is exposed to noise, it is
no more effective than a much lower-rated protector.
[[Page 49606]]
[GRAPHIC] [TIFF OMITTED] TR13SE99.005
Many commenters oppose mandatory use of hearing protectors because
they believe that they would interfere with the aural detection of
warning signals and alarms at mine sites. Also, some commenters believe
that the use of hearing protectors hampers an underground coal miner's
ability to hear sounds generated by changing stresses in the geologic
structure of the mine--commonly known as ``roof talk.'' MSHA
acknowledges that miners need to be aware of the location and movement
of equipment in the mining environment. These commenters stated that
the ability to hear these sounds allows miners to retreat from an
unsafe area before the roof collapses, saving their lives and the lives
of others wearing hearing protectors. These commenters submitted
anecdotal information to MSHA in support of their position. Other
commenters were concerned that hearing protectors limit the ability of
miners to communicate, hear warning signals, and properly operate
mining machinery. Still others, however, stated that miners can hear
roof talk while wearing hearing protectors, and that roof fall
accidents could not have been prevented if hearing protectors had not
been worn.
The rulemaking record contains evidence from which MSHA concludes
that for persons with normal hearing, the use of hearing protectors
will not interfere with the aural detection of warning signals and
alarms at mine sites. Nixon and Berger (1991), have concluded that
``[h]earing protection devices equally attenuate the levels of both the
noise of the environment and auditory signals. An auditory warning
signal may sound different when a hearing protection device is worn,
yet recognition is ordinarily the same whether the ears are protected
or unprotected.'' Prout et al. (1975), found that hearing protectors do
not generally prevent a miner from hearing and analyzing roof talk when
the noise level is high enough to require hearing protectors, but they
diminish the ability to interpret roof warning signals in quiet. Thus
hearing protectors should not be worn in quiet conditions. In addition,
Berger (1986) found that the use of hearing protectors by persons with
normal hearing had no significant effect on the ability to detect
warning signals and that for persons with non-normal hearing,
``[w]arning sounds may be adjusted in pitch and loudness to achieve
optimum perceptibility.'' Berger (1986) also referenced additional
studies which showed that the use of hearing protectors reduced rather
than increased the number of industrial mishaps.
The U.S. armed services and many international communities have
specified sound levels above which hearing protectors must be worn.
However, MSHA concludes that requiring specific trigger levels for
hearing protectors in specific circumstances would be burdensome and
require mine operators to conduct a comprehensive survey on each piece
of equipment. Instead, the Agency is taking the more practical approach
of requiring mine operators to ensure through their policies that
hearing protectors are worn whenever noise-producing equipment is
operating in the miner's work area and that miners are permitted to
remove their hearing protectors in areas with low sound levels. This
should minimize communication difficulties and the sense of isolation
caused by wearing hearing protectors in such areas.
The final rule does not adopt proposed Sec. 62.120(b)(3), which
would have required mine operators to provide hearing protection, upon
request, to a miner whose exposure exceeded the action level. Because
the final rule requires mine operators to enroll miners whose exposures
equal or exceed the action level, and hearing protectors are provided
to miners as a part of that program, the proposed requirement is
unnecessary, and has not been adopted in the final rule.
Section 62.170 Audiometric Testing
This section of the final rule establishes requirements for the
audiometric testing conducted as part of the hearing conservation
program under Sec. 62.150 of the final rule. Included in this section
are specific qualification requirements for persons who conduct
audiometric testing; a requirement that audiometric testing performed
under this part be offered at no cost to the miner; and procedures for
baseline audiograms, annual audiograms, and revised baseline
audiograms.
The requirements in this section of the final rule are nearly
identical to the requirements of proposed Sec. 62.140, with a few
relatively minor changes that are described in detail below. This
section requires that audiometric tests performed to satisfy the
requirements of part 62 be provided by the mine operator at no cost to
the miner, and be conducted by a physician or an audiologist, or by a
qualified technician under the direction of a physician or an
audiologist. Section 62.101 of the final rule defines ``audiologist''
as a
[[Page 49607]]
professional specializing in the study and rehabilitation of hearing,
who is certified by the American Speech-Language-Hearing Association or
licensed by a state board of examiners. ``Qualified technician'' is
defined in Sec. 62.101 of the final rule as a technician who has been
certified by the Council for Accreditation in Occupational Hearing
Conservation (CAOHC) or another recognized organization offering
equivalent certification. A number of comments were received regarding
the appropriate qualifications for audiologists or technicians who
perform audiometric testing. These issues are discussed in greater
detail in the preamble under Sec. 62.101, addressing the definitions
provided in that section.
Commenters disagreed as to what qualifications were necessary for
physicians performing audiometric testing. Some commenters were
concerned that physicians may not have the specific knowledge necessary
to conduct audiometric testing, while other commenters believed that
physicians were appropriately qualified. Several commenters stated that
many, if not most, physicians do not have the training, the expertise,
or the equipment to perform the audiometric testing called for under
this part. Some commenters suggested that physicians conducting
audiometric testing under the final rule be required to be board-
certified otolaryngologists; others were of the opinion that the final
rule should require that physicians conducting the testing have
expertise in hearing and hearing loss. Several commenters preferred a
requirement for both certification and licensure or that the physician
be an otolaryngologist or an otologist. However, MSHA recognizes that
many miners working in outlying areas may not have easy access to an
audiologist who is both licensed and certified.
The final rule does not adopt the suggestion of some commenters
that minimum qualifications be included in the rule for physicians who
conduct audiometric testing. MSHA recognizes that a license to practice
medicine does not guarantee that a physician has the specialized
training or experience needed to conduct audiometric testing, evaluate
audiograms, and supervise those technicians who perform such
activities. However, states enforce stringent medical licensing
requirements, and the medical profession maintains a high degree of
accountability for physicians and has established strict ethical
standards for medical practitioners. In light of these controls, the
Agency expects physicians to exercise professional judgment in
assessing whether they possess the experience and qualifications to
conduct audiometric testing and evaluate audiograms. The final rule
therefore does not adopt commenters' suggestions that additional
licensing or qualification requirements be established for physicians
conducting audiometric testing and evaluating audiograms.
The final rule adopts the proposed requirement that qualified
technicians conducting audiometric tests be under the direction or
supervision of a physician or an audiologist. Although the final rule
does not require that the physician or audiologist be present when the
technician conducts the audiometric testing, the physician or
audiologist must oversee the activities of the technician enough to
ensure adherence to the appropriate test procedures.
This section provides that all audiometric tests performed pursuant
to part 62 must be provided by the mine operator at no cost to the
miner. This requirement essentially adopts the proposed requirement
that participation in a hearing conservation program would be provided
by the mine operator at no cost to the miner. The proposed elements of
a hearing conservation program would have included the annual
audiometric testing and required follow-up examinations and actions.
Baseline Audiogram
The requirements in paragraphs (a)(1) through (a)(3) of Sec. 62.170
of the final rule are derived from virtually identical requirements in
proposed Sec. 62.140(b). Under these requirements:
(1) A miner enrolled in a hearing conservation program must be
offered an audiometric test within specified time periods to establish
a valid baseline audiogram;
(2) The mine operator must provide the miner with a 14-hour quiet
period prior to the baseline audiogram; and
(3) Revisions in the miner's baseline audiogram are not permitted
because of changes in the miner's enrollment status in the hearing
conservation program. However, a new baseline may be established for a
miner who is away from the mine for more than 6 consecutive months.
Unlike the proposal, the final rule allows the use of hearing
protectors as a substitute for the 14-hour quiet period.
Commenters who addressed the issue of audiometric testing generally
acknowledged the need for a valid baseline audiogram as part of an
effective hearing conservation program. However, commenters disagreed
on whether audiometric testing under the final rule should be mandatory
and on the appropriate time frame for establishing the miner's
baseline. Some commenters suggested pre-employment audiograms be used
as the baseline.
The final rule, like the proposal, requires mine operators to offer
miners whose noise exposure exceeds the action level the opportunity
for audiometric testing to establish a baseline and at least annually
after the baseline has been established. The proposed rule would have
also required, under Sec. 62.120(c)(2)(ii), that mine operators ensure
that a miner whose exposure to noise exceeded the permissible exposure
level actually submitted to the audiometric testing offered as part of
the hearing conservation program. MSHA proposed this mandatory testing
requirement for several reasons, including a concern that without
mandatory testing, standard threshold shifts and reportable hearing
losses would go undetected. MSHA was also concerned that a voluntary
program might have a low rate of participation. Finally, the Agency was
concerned that unless participation was mandatory, the costs of miner
testing would provide an incentive for mine operators, who will bear
the costs of such testing, to discourage miners from participating.
MSHA recognized that this provision would be controversial for many in
the mining community, and specifically solicited comments on this issue
in the proposed preamble.
The mandatory audiometric testing requirement has not been adopted
in the final rule, in response to a number of commenters who were
opposed either to any type of mandatory audiometric testing or to
placing the burden on the mine operator to ensure that the miner submit
to such testing. Some commenters stated that mine operators could not
force miners to take hearing examinations. These commenters believed
that mine operators should be required to offer miners such testing,
but should not be penalized if miners do not take advantage of the
offer. Other commenters believed that MSHA should directly require
miner participation in the testing, not put the responsibility on the
mine operator to see that miners participate. Finally, one other
commenter believed that forcing a miner to participate in an
audiometric testing program may violate existing labor contracts.
A number of commenters supported the concept of mandatory
audiometric testing. One commenter stated that audiometric testing is
essential to assess an employee's hearing and determine future changes
in hearing sensitivity.
[[Page 49608]]
This commenter further stated that the audiogram could therefore not be
an optional medical evaluation, but is the keystone of a comprehensive
hearing conservation program. Other commenters were of the opinion that
if audiometric testing were voluntary, miners would be sent the wrong
message and a mine operator's efforts to run an effective hearing
conservation program would be undermined. These commenters further
stated that if audiometric testing is voluntary and a miner refuses the
offer of an audiogram, any hearing loss should be presumed to be non-
work-related. Another commenter questioned whether a miner would have
the right to refuse to participate in an audiometric testing program.
This commenter stated that if a miner could refuse, mine operators
would be placed at a disadvantage in monitoring work-related hearing
loss, and be subject to unwarranted workers' compensation claims. This
commenter was also concerned that, without mandatory audiometric
testing, mine operators would be unable to collect accurate data to
identify hearing-related problems, hampering mine operators' ability to
take appropriate corrective action to provide a healthier workplace.
MSHA notes that the commenters who supported the concept of
mandatory audiometric testing for miners varied greatly as to when such
tests should be required. A number of commenters believed that
audiometric testing should be mandatory for miners whose noise
exposures equal or exceed the action level, and that all miners
enrolled in a hearing conservation program should be required to submit
to audiometric examinations. Other commenters supported mandatory
audiometric testing for all miners, regardless of their noise
exposures. One commenter who supported mandatory testing stated that
the Americans with Disabilities Act (ADA) protects miners from
discrimination based on hearing disability, and any confidentiality
concerns would be addressed both by the ADA and the protections in the
proposed rule.
MSHA has concluded that mandatory audiometric testing is
inappropriate at all levels of noise exposure, based on several
considerations. MSHA acknowledges the concerns of the commenters who
believe that a voluntary audiometric testing program could allow miner
hearing loss to go undetected and unaddressed. However, MSHA is
reluctant to require miners, either directly or indirectly, to submit
to medical examinations that they do not wish to undergo. MSHA is also
reluctant to require miners to submit to testing when the miners may
have concerns about the privacy and confidentiality of audiometric test
records and follow-up evaluations. MSHA also believes that a miner who
voluntarily participates in audiometric testing will more likely wear
hearing protectors, maintain engineering noise controls, and comply
with administrative noise controls. Mine operators remain free to make
audiometric testing mandatory for their miners. However, a miner's
refusal to participate in a mandatory audiometric testing program would
be a labor-management issue rather than an MSHA enforcement issue, and
is outside the scope of this rule.
Under Sec. 62.120 of the final rule, mine operators must enroll
miners whose exposure to noise exceeds the action level in a hearing
conservation program, and offer those miners the opportunity for
regular audiometric tests. Information from these tests indicating that
miners are experiencing hearing loss should prompt both the mine
operator and the Agency to examine the effectiveness of existing noise
controls. For example, if a miner incurs a standard threshold shift,
the mine operator, at the very minimum, should ensure that a hearing
protector is provided to and worn by the miner (see preamble for
Sec. 62.160(c)(1) for further discussion). If the miner already has a
hearing protector, the mine operator should determine whether the
hearing protector needs to be changed. The information obtained through
audiometric testing may indicate the need to pinpoint the source of the
noise causing the problem, and may reveal an undetected failure of
existing noise controls, failure to properly fit, maintain or utilize
hearing protectors, or failure of the training to provide adequate
instruction.
Paragraph (a) of Sec. 62.170 of the final rule, like the proposal,
requires that a miner be offered the opportunity for audiometric
testing to establish a baseline audiogram, against which subsequent
annual audiograms can be compared. An existing audiogram may be used as
the baseline audiogram if it meets the audiometric testing requirements
of Sec. 62.171 of the final rule. OSHA also accepts existing audiograms
as a baseline because, in most cases, use of an existing baseline
audiogram is more protective for the employee. Establishing a miner's
baseline after the miner has been exposed to high levels of noise for
many years is likely to result in less protection for the miner,
because the new audiogram would typically show higher thresholds.
Consequently, the true extent of future hearing losses would appear
smaller than if they had been compared to a baseline that had been
established prior to the years of noise exposure.
A few commenters believed that the audiogram should be conducted
within 12 months of the effective date of the rule to be considered a
baseline. Other commenters believed an existing baseline should be
used; otherwise, experienced miners would be placed at a disadvantage
if their baselines were established after the implementation of the
final rule.
MSHA encourages the use of existing audiograms as baselines
because, as explained above, this approach would provide a greater
degree of protection for the affected miner. Therefore, the final rule
adopts the proposed provision that permits the use of existing
audiograms as the baseline at the discretion of the mine operator, if
the audiograms meet the testing requirements of this part. MSHA
acknowledges the concerns of commenters about miners who may already
have incurred a hearing loss before the effective date of the final
rule, whose hearing loss may not be accurately assessed if new baseline
audiograms are used under this rule. However, the establishment of a
comprehensive scheme that addresses existing hearing loss among miners
is outside the scope of the final rule, whose purpose is the prevention
of occupational noise-induced hearing loss among miners and the
reduction of the progression of such hearing loss.
Paragraph (a)(1) adopts the proposed requirement that the
audiometric testing which results in a baseline audiogram be offered to
the miner within 6 months of enrollment of the miner in a hearing
conservation program, or, if mobile test vans are used, within 12
months of the miner's enrollment. These requirements are consistent
with the requirements of OSHA's noise standard. MSHA's existing noise
standards for coal mines do not specify a deadline for baseline
audiograms for those miners under a hearing conservation plan, and the
existing noise standards for metal and nonmetal mines do not require
baseline audiograms.
Commenters offered differing views on the appropriate period within
which a baseline audiogram should be conducted. One commenter believed
that a miner's audiometric baseline should be determined within 90 days
of the miner's enrollment in the hearing conservation program, rather
than 6 months or a year. Others were of the opinion that 6 months for a
baseline (12 months if a mobile test van is used) established in the
proposal was a
[[Page 49609]]
reasonable deadline. In contrast, the National Institute for
Occupational Safety and Health (NIOSH) has recommended that baseline
audiograms be conducted within 30 days of enrollment in a hearing
conservation program, even if a mobile test van is used. NIOSH believes
that waiting up to 6 months for a baseline audiogram is unacceptable,
because exposure to high sound levels for a relatively short period of
time can adversely affect the hearing sensitivity of susceptible
individuals. Other commenters advocated the use of pre-employment
audiometric testing, under the rationale that such examinations should
be part of the battery of tests conducted when a miner is hired. These
commenters believed that there is a need to document a miner's existing
hearing loss at the point that the miner is hired, so that mine
operators can establish what part of a miner's hearing loss can be
attributed to noise exposure at that mine. Another commenter requested
that the first annual or periodic audiogram conducted after the
effective date of the noise rule should be considered the baseline
audiogram.
Baseline audiograms provide an essential point of comparison for
subsequent audiograms, and are critical in determining the extent of a
miner's hearing loss. If the baseline audiometric test is not conducted
properly and at the appropriate time, it may not accurately reflect the
miner's hearing thresholds, and any changes between the baseline
audiograms and subsequent audiograms may be masked. Because of the
importance of the baseline audiogram, it is highly desirable to conduct
the baseline testing before a miner is exposed to hazardous noise.
MSHA has determined that a deadline of 6 months (or 12 months if a
mobile test van is used) for obtaining the baseline audiogram is
reasonable. This is because in many cases it is not possible to conduct
it any sooner due to the remote location and intermittent operation of
many mines and to the unavailability of adequate audiometric testing
facilities. MSHA recommends that testing should take place as soon as
possible.
The 12-month period for testing by a mobile van allows mine
operators to schedule baseline and annual audiograms simultaneously,
and thus substantially reduce the cost when mobile test vans are used.
The 12-month deadline for mobile van testing recognizes that there may
be significant logistical and scheduling considerations in a visit to a
mine by a mobile test van. Scheduling may need to be done months in
advance.
It should be noted that Sec. 62.160(c)(2) of the final rule
requires mine operators not only to provide all miners enrolled in a
hearing conservation program with hearing protectors, but also to
ensure the hearing protectors are used if the baseline audiogram cannot
be conducted within the 6-month deadline. The final rule's requirements
for baseline audiograms, including the use of hearing protectors, are
consistent with the OSHA rule.
14-hour Quiet Period
Paragraph (a)(2) of Sec. 62.170 of the final rule has been adopted
with a substantive change from proposed Secs. 62.140(b)(2) and (b)(3).
This paragraph, like the proposal, requires that the mine operator
notify the miner of the need to avoid high levels of noise for at least
14 hours immediately preceding the baseline audiogram. This paragraph
also requires that the mine operator not expose the affected miner to
workplace noise for at least a 14-hour period immediately prior to
receiving the baseline audiogram. The final rule, unlike the proposal,
allows the use of hearing protectors as a substitute for this quiet
period. Although existing MSHA standards for noise do not include
provisions for a quiet period before a baseline audiogram, these
requirements are similar to a provision in OSHA's noise standard.
The 14-hour quiet period provides a miner's hearing sufficient rest
to allow recovery from any temporary elevation of hearing levels due to
noise exposure (temporary threshold shift) caused by pre-test noise
exposure. Hearing levels return to normal after a period of quiet. If
the baseline audiogram is skewed by a temporary threshold shift,
compari-
sons of the baseline to subsequent annual audiograms will not provide
an accurate indication of the extent of damage incurred during the time
between the baseline and subsequent tests. It is critical that a
miner's baseline audiogram reflect no temporary threshold shift.
Otherwise, it will be essentially impossible to determine the magnitude
or progression of future hearing loss.
Some commenters supported extending the quiet period requirement to
annual audiograms as well as baseline audiograms. Other commenters
opposed a mandatory 14-hour quiet period, maintaining that requiring
miners to be protected from workplace noise prior to the baseline test
was unreasonable for mines with extended shifts. In those mines, unless
the miner missed all or part of the work shift, he or she would not
receive 14 hours of quiet time. This would severely disrupt the
operation of those mines. Another commenter questioned how a mine
operator could possibly ensure that a miner was not exposed to high
levels of non-occupational noise.
MSHA agrees that the mine operator has no control over a miner's
exposure to noise away from work. However, the training required under
the final rule should encourage miners to avoid high noise exposures
off the job before audiometric testing. One commenter also suggested
that the 14-hour quiet period be reduced to 12 hours, because it would
minimize any interference with normal work shifts.
Research has been conducted on the length of the hearing recovery
period from a temporary threshold shift due to exposure to noise. Fodor
and Oleinick (1986), in their study on workers' compensation programs
in the United States, reported that the initial recovery from a
temporary threshold shift appeared to be very rapid at the end of the
noise exposure, but that the rate of recovery appeared to slow as time
went on. Most researchers, however, report complete recovery from a
temporary threshold shift taking no longer than 16 hours, provided that
the temporary threshold shift did not exceed 40 dB. On the other hand,
some states require that a worker be away from noise exposure for 6
months before hearing loss is evaluated for workers' compensation
purposes. Standards of the U.S. Navy require a quiet period of at least
14 hours, and the U.S. Air Force requires a 15-hour quiet period before
audiometric testing.
After consideration of all of the comments and a review of the
available scientific literature on the subject, MSHA has concluded that
a quiet period is necessary to obtain a valid baseline audiogram, and
that a 14-hour quiet period is the most appropriate of several
alternatives. This conclusion is consistent with the requirements in
OSHA's noise standard and should provide sufficient time to avoid or
recover from a temporary threshold shift before the baseline audiogram
is conducted.
A quiet period of longer than 14 hours would place an undue burden
on mine operators, because in many instances the miner would have to
stay away from the work site to comply with the quiet period when the
miner works a slightly extended shift; many work shifts exceed 8 hours,
especially when a lunch period is taken into account.
The proposal, like the final rule, prohibits the exposure of miners
to ``workplace noise'' during the 14-hour quiet period. Several
commenters requested a definition for ``workplace
[[Page 49610]]
noise,'' suggesting that the final rule provide that miners would be
considered to be protected from ``workplace noise'' if they are not
exposed to noise above the action level or above the permissible
exposure level.
Two researchers, Shaw (1985) and Suter (1983), contend that sound
levels must be below 72 dBA to be considered ``effective quiet.''
Schwetz et al. (1980) found that a sound level below 85 dBA is needed
for recovery from a temporary threshold shift. Studies have shown that
individuals with a temporary threshold shift recovered their normal
hearing more quickly when exposed to a 75-dBA sound level than they did
when they were exposed to an 85-dBA sound level. The 1972 NIOSH
Criteria Document recommends a sound pressure level of 65 dB as
``effective quiet,'' based on work by Schmidek et al. (1972). Hodge and
Price (1978) concluded that a sound level must fall below 60 dBA to
provide effective quiet and not contribute to the development of a
temporary threshold shift.
Recovery from a temporary threshold shift requires exposures below
80 dBA, and based on scientific studies, extended exposure to noise
above 80 dBA may lead to a material hearing impairment. MSHA has
therefore concluded that an acceptable definition of ``workplace
noise'' is a sound level that exceeds 80 dBA, without taking into
account the noise reduction provided by a hearing protector.
Because the mine operator has no control over the non-occupational
noise exposure of a miner, the final rule does not limit non-
occupational noise to a specified sound level during the quiet period;
however, as noted below, the final rule does require that the mine
operator notify miners of the need to avoid high levels of noise during
the 14-hour period preceding the test. It is to the miner's benefit to
limit non-occupational exposure to noise in order to obtain accurate
audiometric testing.
As mentioned above, the final rule, unlike the proposal, adopts the
suggestion of a number of commenters to permit the use of hearing
protectors as a substitute for the quiet period. The specific
prohibition against hearing protectors as a substitute for a quiet
period in Sec. 62.140(b)(2) of the proposal elicited a number of
comments. Many commenters believed that the use of hearing protectors
should be allowed because they would provide adequate protection for
miners. Many also believed that a mandatory 14-hour quiet period would
be impractical without the use of hearing protectors. Several
commenters advocated that hearing protectors be permitted to be used to
satisfy the 14-hour quiet period providing the following conditions
were met: required retraining of the miner on the use of hearing
protectors within 5 days prior to the baseline audiogram; a requirement
that an earmuff-type hearing protector or a foam earplug be used, and
that the protector be in satisfactory condition; and mandatory use of
dual hearing protectors if the noise exposure exceeds 100 dBA. Many of
the commenters who opposed the use of hearing protectors as a quiet
period substitute were those who opposed the use of hearing protectors
for any reason (see the preamble discussion of engineering and
administrative controls under Sec. 62.130). As discussed elsewhere,
although hearing protectors are not as effective as engineering and
administrative controls in protecting miners, MSHA has concluded that
they have an appropriate place in a hearing conservation scheme.
OSHA's noise standard allows the use of hearing protectors as an
alternative to the 14-hour quiet period prior to the baseline
audiogram, under the rationale that they may provide sufficient noise
reduction to prevent a noise-induced temporary threshold shift from
contaminating a baseline audiogram, and that the previous restriction
on hearing protectors as a quiet period substitute was unnecessarily
restrictive.
MSHA's final rule is consistent with OSHA's noise standard in that
it allows hearing protectors to be substituted for the 14-hour quiet
period prior to the baseline audiogram. Although MSHA recognizes that
this decision may result in some miners having measured thresholds that
are higher than their actual thresholds, as a result of exposure to
some high sound levels, the magnitude of the elevated thresholds should
be small unless the noise exposure is severe.
Data indicate that in order to prevent contamination of the
baseline, the sound levels encountered during the quiet period would
need to be below 80 dBA. MSHA is particularly concerned with the
ability of hearing protectors to reduce noise to such low levels. Some
researchers have concluded that even an 80 dBA level may be inadequate
to protect the most susceptible individuals. However, MSHA has
concluded that prohibiting the use of hearing protectors to fulfill the
14-hour quiet period is too impractical a restriction for most mine
operators. Such a restriction may be too disruptive of the operations
at many mines. Hearing protectors that are correctly fitted and used
should provide an acceptable quiet period. The final rule, like OSHA's
noise standard, therefore allows the use of hearing protectors as a
substitute for the 14-hour quiet period.
MSHA nonetheless strongly recommends that mine operators make
reasonable attempts to provide a quiet period for miners before their
baseline audiogram, instead of relying on hearing protectors. For
example, a mine operator could provide a miner with a quiet period by
scheduling the baseline audiogram after a miner's regularly scheduled
day off or immediately following a weekend during which the miner does
not work. This avoids any disruption of operations, while at the same
time ensuring that the audiogram is not contaminated.
Sound Level Avoidance
Paragraph (a)(2) of Sec. 62.170 of the final rule, like
Sec. 62.140(b)(3) of the proposal, requires mine operators to notify
the miner of the need to avoid high levels of noise during the 14-hour
period immediately preceding the baseline audiogram. This requirement
is identical to provisions in OSHA's noise standard.
Only a few commenters addressed this issue. Some commenters agreed
that workers need to be advised to avoid non-occupational noise
exposure prior to taking the baseline audiogram. Several commenters
were concerned that notifying the miners to avoid high levels of noise
could lead to fraud in workers' compensation cases. These commenters
were concerned that miners might intentionally expose themselves to
high levels of noise prior to the baseline audiogram in order to
provoke a temporary threshold shift and eventually receive an award of
compensation. MSHA expects that competent audiologists and physicians
will be able to determine if a miner has purposely incurred a temporary
threshold shift.
The 1983 preamble to revisions to OSHA's noise standard (48 FR
9757) reflects OSHA's conclusion that the likelihood of non-
occupational noise exposure contaminating the baseline audiogram can be
substantially reduced by counseling workers of the need to avoid such
exposures in the period before their baseline tests. MSHA agrees with
OSHA's conclusion regarding worker notification, and the final rule
reflects this determination. It should be noted that the final rule
does not require written notification. However, it may be in a mine
operator's interest to put the notification in writing, because it
provides the mine operator with proof of notification.
[[Page 49611]]
Exceptions for Revising Baseline Audiograms or Revised Baseline
Audiograms
The requirements of paragraph (a)(3) of Sec. 62.170 of the final
rule are nearly identical to proposed Sec. 62.140(b)(4) in that a mine
operator must not establish a new baseline audiogram or revised
baseline audiogram, where one has been established, due to changes in
the miner's enrollment status in the hearing conservation program.
However, baseline audiograms may be revised if a miner is away from the
mine for a period of time exceeding 6 consecutive months. OSHA's noise
standard does not contain such a requirement. This restriction is
intended to ensure that a new baseline audiogram is not established or
a miner's baseline audiogram is not revised even if a miner moves in
and out of enrollment in a hearing conservation program because of time
away from the mine due to unemployment or extended periods of vacation.
Otherwise, a miner's incremental losses of hearing may be erased by
revised baseline audiograms, and the true extent of a miner's hearing
loss may escape accurate measurement.
Some commenters believed a new baseline should be established if
the affected miner is away from the mine for at least 6 or 12 months.
Another commenter stated the mine operator should be allowed to obtain
a new baseline for a miner who returns to work after working for
another mine operator, regardless of how long the miner had been away.
These commenters were concerned about being held responsible for a
miner's hearing loss that results from overexposure to noise during
other employment. A large number of contract and transient employees
work in the mining industry. Additionally, many metal and nonmetal
mines operate seasonally or otherwise intermittently throughout the
year. As a result, a large number of miners are typically away from the
job site for long periods of time. MSHA agrees that mine operators
should not be held responsible for a miner's hearing loss incurred
during employment at other mines or during extended periods of
unemployment. Therefore, the final rule adopts the proposed provision
that allows for the revision of the baseline audiograms or revised
baseline audiograms, where one has been established, for those miners
who have been away from their employment at a particular mine for
periods longer than 6 consecutive months.
Annual Audiogram
Paragraph (b) of Sec. 62.170 of the final rule adopts the
requirement of Sec. 62.140(c) of the proposal that, after the baseline
audiogram has been established, the mine operator must continue to
offer the miner subsequent audiometric tests every 12 months as long as
the miner remains enrolled in a hearing conservation program.
Existing MSHA standards for metal and nonmetal mines do not require
audiometric testing. Under existing standards for coal mines, pre-
employment and periodic audiograms are offered to miners at mines
operating under a hearing conservation plan, but no procedures or time
frames for these audiograms are specified (although MSHA policy
provides that periodic audiograms must be offered at least every two
years). Because MSHA policy has allowed consideration of the noise
reduction value of hearing protectors to be considered when determining
compliance with the permissible exposure level in coal mining, few coal
mines have hearing conservation plans, and only one percent of coal
miners are currently covered by such plans.
Some commenters supported annual audiometric testing, while several
others supported periodic audiometric testing but recommended different
intervals, ranging from once a year to once every three years depending
upon the severity of the noise exposure or of the existing hearing
loss. However, none of these commenters offered suggestions for the
relationship between the severity of a miner's noise exposure and the
frequency of audiometric testing. One commenter requested clarification
as to whether the annual audiometric tests would be required to be
administered once each year or once each 12 months. Several commenters
questioned how a mine operator could be protected from liability for
non-occupational hearing loss that occurs between the annual
audiometric tests. Once baseline audiograms have been obtained, OSHA
requires that an audiogram be offered annually to each employee exposed
at or above the action level in order to identify changes in hearing
sensitivity. This allows the use of hearing protectors to be prescribed
or other follow-up measures initiated before the miner's hearing loss
can worsen. OSHA adopted the annual audiometric test requirement
because of the potential seriousness of the hearing damage that can
occur within a 2-year period, before the hearing loss is identified by
an audiogram.
MSHA has concluded that annual audiometric testing is necessary for
evaluating the hearing level of miners whose exposure equals or exceeds
the action level for extended periods of time. These annual audiograms
can be used to detect changes in a miner's hearing sensitivity, thus
triggering several important actions provided for in the final rule.
For example, retraining of the miner could be required. If a miner is
enrolled in the hearing conservation program as a result of noise
exposure at or above the action level, but the miner's noise exposure
is below the permissible exposure level, detection of a standard
threshold shift will require the mine operator to provide the miner
with a hearing protector and ensure its use. If a miner is already
using a hearing protector, the miner must be allowed to select a
different hearing protector. Detection of a standard threshold shift
also requires reevaluation of the engineering and administrative
controls being used at the mine.
With regard to those commenters who were concerned about being held
responsible for non-occupational hearing loss that occurs between
annual audiograms, MSHA has concluded that the physicians or
audiologists who conduct the audiometric tests are in a position to
determine whether any hearing loss detected by the test is due to non-
occupational causes.
The intervals between annual audiometric testing conducted under
the final rule must not exceed 12 months. This means that testing once
every calendar year would not be acceptable unless the interval between
the tests is 12 months or less. For example, an annual audiogram in
January of one calendar year cannot be followed by testing any later
than January of the following calendar year. Otherwise, the interval
between annual audiograms could extend to nearly 24 months, an
unacceptably long time period, for the reasons explained above.
After a review of comments, the relevant scientific literature, and
regulations of other governmental agencies, MSHA has concluded, and the
final rule reflects, that annual audiometric testing is both necessary
and appropriate, and is an integral part of a comprehensive hearing
conservation program.
Revised Baseline Audiogram
Paragraphs (c)(1) and (c)(2) of Sec. 62.170 of the final rule,
which have been adopted from proposed Secs. 62.140(d)(1) and (d)(2),
require that the mine operator establish a revised baseline audiogram
when:
[[Page 49612]]
(1) the standard threshold shift revealed by the annual audiogram
is persistent; or
(2) the hearing threshold shown in the annual audiogram indicates
significant improvement over the baseline audiogram.
These requirements are the same as those in OSHA's noise standard,
and, in response to commenters, MSHA has adopted the term used by OSHA
of ``revised baseline audiogram'' rather than ``supplemental baseline
audiogram'' used in the proposed rule.
Many commenters favored revising the baseline if a standard
threshold shift is persistent. Several commenters suggested that MSHA
adopt the guidelines of the National Hearing Conservation Association
for revising baseline audiograms, to establish some consistency in
determinations.
MSHA has concluded that allowing revision of the baseline after a
standard threshold shift has been identified will prevent the same
standard threshold shift from being identified repeatedly. The annual
audiogram on which the standard threshold shift is identified then
becomes the revised baseline audiogram. In addition, MSHA intends that
each ear be treated separately when the baseline audiogram is revised.
If the baseline is revised for both ears when only one has a standard
threshold shift, detection of a standard threshold shift in the other
ear may not be possible, even if the miner has lost a substantial
amount of hearing sensitivity.
Under the final rule, the revised baseline audiogram should be
compared with future annual audiograms to identify a second standard
threshold shift. The original baseline audiogram continues to be used
to quantify the total hearing loss, and is considered in determining
whether the hearing loss constitutes a ``reportable hearing loss.''
Some commenters favored revising the baseline if the annual
audiogram showed an improvement in hearing. One commenter recommended
that a revised baseline be permitted only if the improvement in the
miner's hearing was consistent for multiple consecutive tests. Another
commenter stated that MSHA should not adopt the provision for revised
audiograms in the final rule, because hearing sensitivity does not
improve with noise exposure or increasing age. While it is true that
hearing sensitivity does not improve; MSHA recognizes that audiometric
tests can sometimes reflect an apparent improvement. Under the final
rule, MSHA leaves it to the professional judgement of the medical
professional or audiologist to conduct multiple tests to confirm that
the apparent improvement is real.
Paragraph (c)(2) requires revision of the baseline if the annual
audiogram shows significant improvement in hearing level. This
provision has been adopted unchanged from the proposal, and provides
additional protection to the miner because it allows more accurate
evaluation of the true extent of hearing loss that may occur in the
future. When a baseline audiogram is revised due to an improvement in
hearing sensitivity, the revised baseline must be considered the
original baseline for determining when a standard threshold shift
occurs and for quantifying the total reportable hearing loss under part
50. The latter is reflected in Sec. 62.101 of the final rule, under the
definition of a ``reportable hearing loss.''
Finally, one commenter suggested that separate baselines be kept
for a standard threshold shift and otologic referrals. This measure is
not needed, however, because the final rule requires that all
audiograms be retained as part of the audiometric test record under
Sec. 62.171(b)(2). Revision of the baseline audiogram does not permit
the destruction of the original baseline audiogram.
Temporary and Seasonal Miners
In the preamble to proposed Sec. 62.120, MSHA solicited comments on
how to best protect temporary or seasonal miners whose occupational
noise exposures equal or exceed the action level. MSHA raised this
issue because mines producing certain commodities, such as sand,
gravel, and crushed stone frequently cease operations during the winter
months. As a result, miners at these operations may only work part of
the year, and protecting the hearing of these miners can be extremely
problematic, given the long periods when miners are away from the mine
site.
Some commenters believed that the fact that the proposal would
allow mine operators 6 months to arrange for miners to receive baseline
audiograms would effectively exclude most temporary or seasonal miners,
because their employment relationship with the mine operator would end
before the deadline for their audiometric testing had passed. Other
commenters suggested that the use of hearing protectors on the job
would adequately protect temporary miners from experiencing an
occupational noise-induced hearing loss. One commenter suggested that
it would be too burdensome for a mine operator to enroll miners who had
worked less than one year in the audiometric testing program. Several
commenters opposed any exemption that would result in temporary miners
receiving less protection than that provided to other miners.
OSHA has no exemption for audiometric testing for temporary or
seasonal workers, and, like the proposal, MSHA's final rule does not
provide any exemption for temporary or seasonal miners from the final
rule's audiometric testing requirements. MSHA has determined that such
an exemption would mean that miners who work intermittently in the
mining industry may never receive an audiometric test to detect hearing
loss, even if they work under very noisy conditions, and would never
receive any of the protections required under the final rule for miners
who have incurred hearing loss.
Although the 6-month time period (12 months where a mobile van is
used) allowed under the final rule for obtaining an audiogram could
effectively exclude many temporary or seasonal miners from the
audiometric testing program, prudent mine operators will offer
audiometric tests to temporary or seasonal miners and not take
advantage of the 6-month period to avoid offering these miners
audiometric tests.
Section 62.171 Audiometric Test Procedures
This section of the final rule establishes the procedural and
recordkeeping requirements for the audiometric testing conducted under
this part. This section specifies the frequencies to be used in the
testing, and requires the mine operator to compile and maintain an
audiometric test record for each miner tested. The requirements of this
section are essentially the same as those proposed in Sec. 62.150, with
several relatively minor changes.
Paragraph (a) of this section of the final rule adopts the proposed
requirement that audiometric testing under part 62 be conducted in
accordance with scientifically validated procedures. MSHA's metal and
nonmetal noise standards do not contain audiometric testing provisions.
While MSHA's noise standards applicable to coal mines require
audiometric testing, they do not include any procedural requirements
for this testing. The final rule does not specify detailed procedures
for audiometric testing, calibration of audiometers, or qualifying of
audiometric test rooms. Instead, the final rule takes a performance-
oriented approach, not only to allow flexibility in compliance but also
to accommodate technology developed in the future. The final rule
[[Page 49613]]
specifies basic parameters for the testing while allowing the physician
or the audiologist to use professional judgment in selecting the
appropriate testing procedures.
This aspect of the proposal generated a significant amount of
comment. Several commenters stated that the proposed requirement that
tests be conducted in accordance with ``scientifically validated
procedures'' was too vague, and recommended that the final rule clarify
or define the phrase ``scientifically validated procedures.'' Some
commenters believed that if the Agency failed to specify the test
procedures that should be followed, audiometric test results would not
be uniform. Other commenters, some of whom strongly supported a
performance-oriented approach to testing procedures, suggested that the
final rule include an appendix specifying the level of testing
performance expected, or at least providing examples of acceptable
procedures that may be followed. Commenters stated that this would
allow mine operators to determine if the procedures they have adopted
comply with the requirements of the final rule.
Several commenters recommended specific changes regarding
audiometric testing, including audiometric test instruments,
calibration procedures, and audiometric test rooms. Several commenters
believed that the audiometric testing procedures required by the final
rule should be identical to OSHA's requirements, which contain detailed
testing procedures in 29 CFR Sec. 1910.95(h) and in associated
appendices. Others recommended that the final rule require audiometric
testing to be conducted in accordance with several standards of the
American National Standards Institute (ANSI), including ANSI S3.21-
1978, ``Methods for Manual Pure-Tone Threshold Audiometry,'' which
provides detailed procedures for conducting audiometric tests; ANSI
S3.1-1991, ``Maximum Permissible Ambient Noise Levels for Audiometric
Test Rooms,'' which provides a criterion for the maximum background
sound pressure levels to obtain a valid audiogram; and ANSI S3.6-1996,
``Specification for Audiometers,'' which provides design criteria for
various classes of audiometers.
Some commenters suggested that MSHA specify calibration procedures
for audiometers. The suggestions included requiring daily calibration
of audiometers as well as annual laboratory calibration. Other
commenters recommended that MSHA specify the maximum background sound
pressure levels acceptable during audiometric testing.
Several commenters suggested, in the absence of a definition for
``scientifically validated procedures,'' that the final rule provide
that if the qualified professional who conducts the audiometric tests
certifies the test's scientific validity, the mine operator is
permitted to rely in good faith on such certification.
After reviewing the comments, the scientific literature, and
several governmental standards, MSHA has concluded that the final rule
should adopt the proposed performance-oriented approach, and should not
include detailed, highly technical procedures and criteria for
conducting audiometric testing in the final rule. Instead, the final
rule adopts the proposed requirement that audiometric testing
procedures be governed by scientifically validated procedures, which
would be any method or procedure that has been proven to be effective
and is generally recognized by experts in the technical field. Such
procedures may be incorporated, for example, into consensus standards,
governmental specifications, or military regulations, including OSHA's
audiometric testing procedures and criteria or the procedures included
in the three ANSI standards referenced above.
MSHA anticipates that most audiograms conducted under the final
rule will employ the procedures specified in OSHA's noise standard, in
large part because many physicians and audiologists are already
familiar with those procedures, and many computer programs used for or
in conjunction with audiometric testing are based on that standard.
Further, many audiology texts and training courses of the Council for
Accreditation in Occupational Hearing Conservation (CAOHC) reference
OSHA's audiometric testing procedures and criteria in detail. OSHA's
audiometric testing requirements and associated appendices can be found
in 29 CFR Sec. 1910.95. To assist the mining community in complying
with the audiometric requirements in the final rule, MSHA will post
OSHA's requirements on our Internet Home Page at www.msha.gov.
Another possible source of acceptable procedures under the final
rule are the recommendations provided by audiometer manufacturers on
audiometer use and calibration (in both the laboratory and the field).
These equipment manufacturers are in a position to issue specific
recommendations on the use and calibration of their audiometers. By
following manufacturer's recommendations, accurate audiometric testing
will be ensured.
Under the final rule the individual who conducts the testing must
have the specialized qualifications of a physician, audiologist, or
technician, all of whom should be knowledgeable and familiar with
scientifically validated procedures and capable of exercising
professional judgment in choosing the appropriate testing procedures.
Further, the final rule allows the use of any scientifically validated
procedure, which provides flexibility for the use of new procedures or
technology that may be developed in the future. This means that if a
new, possibly more accurate, procedure is developed and has been
scientifically validated, the physicians and audiologists who perform
audiometric testing under this part may readily adopt its use.
Test Parameters
Paragraph (a) of Sec. 62.171 of the final rule, like the proposal,
requires that audiometric tests be pure tone, air conduction, hearing
threshold examinations, with test frequencies at 500, 1000, 2000, 3000,
4000, and 6000 Hz. The final rule also requires that each ear is to be
tested separately. This aspect of the final rule is consistent both
with OSHA's requirements for audiometric testing frequencies and with
NIOSH's recommendations in its 1972 Criteria Document. Existing MSHA
regulations do not include any specifications for audiometric testing.
A few commenters directly addressed the audiometric test parameters
in the proposal. Of these, one commenter specifically supported the
test frequencies as proposed. A few other commenters supported the
adoption of the test frequencies either in the OSHA noise standard or
in ANSI S3.21-1978, ``Methods for Manual Pure-Tone Threshold
Audiometry,'' and ANSI S3.6-1996, ``Specification for Audiometers,'' or
a combination of these standards. As stated above, the test frequencies
required by the final rule are identical to those required in OSHA's
noise standard. The ANSI standards include the additional test
frequencies of 250 and 8000 Hz. Other commenters supported adding 8000
Hz to the test frequencies included in the proposal. These commenters
believed that adding the frequency of 8000 Hz would assist the
evaluator of the audiogram in determining the cause of the hearing loss
more accurately. Commenters pointed out that because this frequency is
standard on audiometers manufactured since 1974, inclusion of this
frequency would not
[[Page 49614]]
present a significant burden on the individual conducting the test.
As noted elsewhere in this preamble, noise-induced hearing loss is
a permanent sensorineural condition that cannot be improved medically,
and is characterized by a declining sensitivity to high frequency
sounds. This loss usually appears first and is most severe at the 4000
Hz frequency, and the ``4000 Hz notch'' in the audiogram is typical of
noise-induced hearing loss. Continued exposure causes the loss to
include other audiometric test frequencies, with 500 Hz being the least
affected. While 500, 1000, and 6000 Hz are not included in the
definition of a standard threshold shift, MSHA, like OSHA, believes
that these test frequencies contribute to a more thorough audiometric
profile and are helpful in assessing the validity of the audiogram as a
whole. Testing at 500 and 1000 Hz makes it easier for an audiologist or
physician to differentiate conductive hearing loss from noise-induced
hearing loss, and testing at 6000 Hz allows better differentiation
between age-induced and noise-induced hearing loss, so testing at 8000
Hz is unnecessary. However, this would not prevent testing at
additional frequencies.
Audiometric Testing Records
The requirements of paragraphs (b)(1) through (b)(5) of Sec. 62.171
of the final rule specify which audiometric testing records a mine
operator must maintain. They have been adopted from proposed
Sec. 62.150(c) with one change. Under the final rule mine operators are
required to compile an audiometric test record for each miner tested,
including the miner's name and job classification, copies of all of the
miner's audiograms required under part 62, evidence that the
audiometric tests were conducted in accordance with paragraph (a) of
this section, any exposure determinations for the miner, and the
results of any follow-up examinations. The proposal would have required
the mine operator to obtain a certification from the physician or
audiologist that the audiometric testing had been conducted in
accordance with scientifically validated procedures. In lieu of this
requirement, the final rule provides greater flexibility by requiring
evidence that the audiograms were conducted in accordance with the
final rule's requirements. MSHA's existing standards currently contain
no recordkeeping or record maintenance requirements.
Many commenters raised issues concerning the proposed requirements
for audiometric testing records. Several commenters proposed that MSHA
adopt the requirements of OSHA's noise standard, which requires not
only the name and job classification of the employee, but also the date
of the last acoustic or exhaustive calibration of the audiometer. OSHA
also requires employers or audiometric test service providers to
maintain an accurate record of background sound pressure levels in
audiometric test rooms. However, as discussed above, OSHA's noise
standard includes specific procedures for audiometric testing, and the
additional records required under OSHA's standard are intended to show
that the required procedures have been followed. Without such specific
procedures, these additional records are unnecessary. OSHA's noise
standard, like the final rule, requires that employers maintain a
record of audiometric test results.
One commenter requested clarification of the recordkeeping
requirement, asking if it was limited to individual readings for
specific miners or also included records of area or group monitoring.
The requirement covers only personal noise exposure determinations,
because this information will allow persons evaluating audiometric
testing results to make a better determination regarding the nature of
a miner's hearing loss.
The recordkeeping requirements for audiometric testing in the final
rule provide essential information to MSHA and to health professionals
for the evaluation of a miner's audiogram. The information is also
necessary for identifying the audiograms, for evaluating whether the
audiometric tests have been conducted properly, and for determining
whether the results are valid. Further, the information is critical to
the evaluator in determining whether an identified hearing loss is
occupationally induced or aggravated by occupational noise exposure.
Section 62.150(b) of the proposal would have required mine
operators to obtain a certification from the physician or audiologist
responsible for conducting audiometric tests under this part that such
tests had been conducted in accordance with scientifically validated
procedures. In its place paragraph (b)(3) of this section of the final
rule requires that the audiometric test record include evidence that
the audiometric tests conducted under part 62 have been conducted in
accordance with the scientifically validated procedures required under
paragraph (a) of this section.
One commenter was of the opinion that mine operators should be
allowed to rely on the professionals certifying the audiometric test
results, and should not be held responsible for improper procedures if
they have received a certification from the professional conducting the
test. Another commenter believed that, since the proposal would already
require that the person conducting the test have minimum
qualifications, such a certification would be unnecessary.
Some commenters, who believed that requiring mine operators to
obtain a certification for each individual audiogram was unduly
burdensome, stated that the final rule should allow mine operators to
obtain a certification for a group of audiograms.
The Agency agrees with commenters that the certification
requirement set forth in the proposal would be unnecessarily rigid.
However, MSHA has also concluded that some type of evidence is
necessary to indicate that the audiometric tests conducted under this
part are in accordance with scientifically validated procedures.
Therefore, the final rule provides that audiometric test records
required to be maintained must include evidence that the audiograms
were conducted in accordance with paragraph (a) of this section of the
final rule, which provides that scientifically validated procedures
must be followed. Such evidence could include a letter from a
physician, audiologist, or qualified technician that states which
audiometric test procedures have been followed. A billing record that
indicates the test procedures used would also be acceptable. Finally,
the audiogram itself may include information about the test procedures
used sufficient to satisfy this requirement. Other types of evidence
not listed here may also be acceptable under the final rule, provided
they reflect compliance with the procedural requirements of the final
rule. Evidence that a group of audiograms were conducted in accordance
with required procedures would also be sufficient, provided that it
makes clear which audiograms are involved. This responds to commenters
who believed the proposed requirements, which could have been read to
require an individual certification for each audiogram, were
unnecessarily burdensome.
MSHA agrees that the mine operator would ordinarily not have
sufficient medical knowledge to determine if the tests were properly
conducted, and would ordinarily rely on the physician, audiologist, or
qualified technician to provide the evidence required under this
paragraph. The final rule does hold the mine operator responsible for
obtaining this evidence from these professionals--MSHA assumes that
mine operators, as a result of their
[[Page 49615]]
business or contractual relationships with providers of audiometric
tests, can easily specify that such evidence must be provided as part
of the terms and conditions of the service agreement.
Paragraph (c) of Sec. 62.171 of the final rule, which has been
adopted with two changes from proposed Sec. 62.150(d), specifies the
location and duration for maintenance of the testing records compiled
under paragraph (b). In response to commenters, the final rule does not
adopt the proposed requirement that the records be maintained at the
mine site. The final rule also clarifies that these records must made
be available for inspection by an authorized representative of the
Secretary of Labor. MSHA's existing standards contain no requirements
in this area. OSHA standards require that audiometric testing records,
along with all other employee medical records required to be kept under
OSHA standards, be maintained for at least the duration of the worker's
employment plus 30 years, with the exception of employees who have
worked for less than one year for the employer. Additionally, the OSHA
rule provides that employee medical records need not be retained beyond
the term of employment if they are provided to the employee upon
termination.
MSHA received a number of comments specifically addressing time
frames for maintaining audiometric test records. Commenters recommended
several different periods of record retention beyond the duration of
the miner's employment--6 months, 12 months, or 30 years, which is the
retention period required by OSHA. Requirements for maintenance and
retention of audiometric tests records of the U. S. armed forces,
including the Navy, the Air Force, and the Army, and several foreign
countries require the retention of audiometric test records for at
least the duration of the test subject's employment, and in most cases
for some period of time after the termination of employment.
MSHA's rationale in requiring retention of audiometric test records
for at least 6 months beyond the duration of the miner's employment is
that the miner's risk of occupational hearing loss stops with the
cessation of employment.
Retention of audiometric records for an additional 6 months will
ensure that the records remain available for use by the mine operator
to conduct further evaluations should the miner return to employment
within that period. This 6-month retention period does not place an
unduly heavy paperwork burden on mine operators, but also addresses the
seasonal operations in the metal and nonmetal mining industry, which
cease operations during the winter months every year. MSHA expects that
the periods of unemployment experienced by miners at those operations
generally will not exceed 6 months, thus ensuring that these miners'
audiometric records will be retained throughout their cycles of
employment.
Under the final rule, ``duration of employment'' is the period of
time between the date of a miner's initial hiring and the date on which
the miner is released, quits, retires, or is otherwise separated. There
must be a period of at least 6 months after formal termination of
employment before a mine operator can destroy the audiometric test
records. Moreover, under the final rule, a layoff, strike, lockout,
furlough, period of leave (paid or unpaid), or other temporary break in
service is not considered a formal termination of employment, even if
it exceeds 6 months.
MSHA expects that many mine operators will retain miners'
audiograms long after the miners' employment ceases, because the
records could prove to be relevant if a miner should file a subsequent
workers' compensation claim for hearing loss, especially because some
states allow workers to file such a compensation claim many years after
termination of employment.
Many commenters took issue with the proposed requirement that
audiometric testing records be maintained at the mine site, and
requested that MSHA permit the records to be stored at a site remote
from the mine. These commenters believed maintaining these records at
the mine would be burdensome, and that it may be much more efficient
for many mine operators to store records at a central site, especially
if several small mining operations were in the same general vicinity.
MSHA agrees with the points made by these commenters, particularly
in light of the fact that electronic records are becoming more common
in the mining industry, and may be stored on computer at a centralized
location. The final rule therefore allows mine operators to keep
audiometric test records at a location other than the mine site.
However, the records must be stored within sufficient proximity to the
mine to allow the mine operator to produce them to an MSHA inspector
within a relatively short time. MSHA expects that in most cases this
period will be no longer than one business day.
The final rule also clarifies that these records must be available
for review by an authorized representative of the Secretary of Labor.
MSHA inspectors already have the authority to review records required
to be kept by the Mine Act or by the regulations established under it;
this added language merely affirms this authority.
Section 62.172 Evaluation of Audiograms
This section of the final rule has been adopted unchanged from
proposed Sec. 62.160. It establishes the requirements for evaluating
audiograms conducted under part 62. This section requires that the mine
operator inform the person evaluating the audiogram of the requirements
of this part and provide the evaluator with copies of the miner's
audiometric test records. Additionally, the mine operator is
responsible for having a physician, audiologist, or qualified
technician determine if an audiogram is valid and if a standard
threshold shift or reportable hearing loss has occurred.
This section also includes a provision to protect miners' non-
occupational medical findings or diagnoses from disclosure to the mine
operator and requires a prompt audiometric retest if a miner's
audiogram is invalid. Finally, this section permits, but does not
require, the adjustment of results of audiometric tests for age-induced
hearing loss. Tables for this purpose are included in the final rule.
MSHA's existing noise standards do not address the evaluation of
audiograms. The requirements in this section are similar to the
requirements of OSHA's noise standard; the few differences are noted
below.
A number of commenters noted that, although a doctor can
distinguish hearing loss that has been caused by illness or injury from
hearing loss caused by noise exposure, it is not possible to
distinguish between hearing loss from work-related noise exposure and
from non-work-related noise exposure. These commenters pointed out that
many of their employees were very active during their non-working hours
and had hobbies that could expose them to high sound levels, such as
woodworking, hunting, motorcycling, snowmobiling, etc. These commenters
took issue with the fact that, under the proposed rule, mine operators
would be held responsible for all noise-induced hearing loss,
regardless of whether it is occupationally related. MSHA agrees that
hearing loss may result from many causes, not all of which are
occupationally related. Under the final rule physicians and
audiologists have the obligation to determine if the hearing loss was
the result of or aggravated by occupational noise exposure or a medical
condition aggravated by the use of hearing
[[Page 49616]]
protectors. If the hearing loss is not the result of or aggravated by
occupational noise exposure or aggravated by the wearing of hearing
protectors, mine operators would not be responsible for corrective
action. In addition, the final rule allows correction of audiograms for
hearing loss due to aging.
MSHA acknowledges that determining whether hearing loss is
occupationally related is not always straightforward. However,
physicians and audiologists conducting audiometric testing should
routinely ask about a miner's employment history and both occupational
and non-occupational noise exposures, in order to make reasoned
assessments and conclusions about the source of any hearing loss that
may be detected in the course of audiometric testing. If the miner's
occupational noise exposures are minimal, and yet the miner has
incurred a severe hearing loss, this should indicate to the physician
or audiologist that he or she must look beyond the workplace for the
cause of the hearing loss. The doctor can make an educated
determination that a hearing loss is occupational based on certain
patterns commonly seen in occupational loss. Some of these indicators
are--
1. If the hearing loss is consistent in both ears;
2. If the loss is more severe in the higher speech frequencies;
3. If the patient has a history of exposures to noisy workplaces;
and
4. If the patient has no evidence of illness or injury to the head
or ears and there is no history of familial hearing loss or noisy
pastimes (rock music, motorcycles, hunting). MSHA has concluded that
taking this approach in such instances of uncertainty provides the best
protection for miners.
Paragraph (a)(1) of Sec. 62.172 of the final rule is adopted from
proposed Sec. 62.160(a)(1), and requires that the mine operator inform
the person evaluating the audiogram of the requirements of part 62 and
provide the evaluator with copies of the miner's audiometric test
records.
The intent of this provision is to ensure that physicians and
audiologists are sufficiently familiar with the final rule's
requirements to evaluate miners' audiograms in compliance with the
regulations. For example, the evaluator should be aware of how the
final rule defines a standard threshold shift, the criteria in the
final rule for audiometric retesting or medical follow-up, procedures
for correction for age-induced hearing loss, and recordkeeping
requirements. OSHA's noise standard requires employers to provide the
evaluator of the audiograms with a copy of the requirements of its
standard, copies of the employee's baseline and most recent audiometric
test records, the background sound pressure levels in the audiometric
test room, and a record of audiometer calibrations. Under MSHA's final
rule, the person conducting the audiometric testing and evaluation of
the audiogram is required to use scientifically validated procedures,
and therefore has some discretion over which procedures are used. No
comments were received addressing this aspect of the proposal, and it
has been adopted unchanged in the final rule.
Under paragraphs (a)(2)(i) and (a)(2)(ii) of this section, which
have been adopted from Sec. 62.160(a)(2) of the proposal, the mine
operator must have a physician or an audiologist, or a qualified
technician under the direction or supervision of a physician or an
audiologist, determine if an audiogram is valid and if a standard
threshold shift or reportable hearing loss has occurred. This
requirement is consistent with provisions in OSHA's noise standard.
Several commenters stated that only those physicians with
experience and expertise in hearing and hearing loss should be
permitted to review audiograms. MSHA has concluded that physicians
should be included among those professionals who may evaluate
audiograms, for reasons addressed in greater detail in the preamble
discussion for Sec. 62.170 of the final rule.
Other commenters stated that the final rule should define what
constitutes an invalid audiogram, in light of the fact that physicians,
audiologists, and qualified technicians, under the direction of a
physician or audiologist, are required to determine whether the
audiogram is invalid. One commenter recommended that the final rule
adopt the Head and Neck Surgery referral criteria of the American
Academy of Otolaryngology for determining whether an audiogram is
invalid.
MSHA has not adopted the suggestion above and does not provide a
definition for invalid audiogram, or a list in the final rule of the
deficiencies that could render an audiogram invalid. Instead, the final
rule requires that this assessment be made by qualified professionals--
physicians, audiologists, and qualified technicians--and relies on
their professional judgment and expertise in determining whether an
audiogram is valid. These professionals are free to use whatever
criteria they deem appropriate in making such a determination,
including the American Academy of Otolaryngology referral criteria
referenced above. In any case, it would not be possible to provide an
exhaustive list of indicators of possible invalid audiograms. However,
some factors that may indicate an invalid audiogram include, but are
not limited to: large differences in hearing thresholds between the two
ears; unusual frequency patterns that are not typical of noise-induced
hearing loss; thresholds that are not repeatable; or an unusually large
hearing loss incurred in less than a year.
One commenter advocated that the final rule require the supervising
physician or audiologist to establish specific criteria for a
technician to follow in determining whether the audiogram is valid or a
standard threshold shift or a reportable hearing loss has occurred.
This comment has not been adopted in the final rule, because the rule
already requires that a qualified technician work under the supervision
or direction of a physician or an audiologist. The physician or
audiologist is ultimately responsible under the final rule for ensuring
that the technician performs audiometric testing and evaluation with
the requisite level of proficiency. MSHA has therefore concluded that
it is unnecessary to include a specific requirement for making this
determination.
Another commenter challenged the proposed requirement that the mine
operator instruct the physician, audiologist, or qualified technician
to determine if an audiogram is valid, maintaining that mine operators
should rely on the medical professional's judgement instead.
MSHA agrees with commenters that mine operators typically would not
have the expertise to determine the validity of an audiogram. However,
the final rule places on mine operators the responsibility to ensure
that miners are protected from occupational hearing loss. One part of
an effective hearing conservation program is regular audiometric
testing for miners at risk, and MSHA has concluded that it is
appropriate to require mine operators to ensure that the professionals
who conduct and evaluate audiometric tests do so in accordance with the
requirements of the final rule.
Paragraph (a)(2)(ii) also requires the evaluator of the audiogram
to determine whether a miner has incurred a standard threshold shift in
hearing. Determination of a standard threshold shift triggers specific
remedial actions, designed to prevent additional hearing loss.
Commenters raised a number of issues concerning the appropriate
definition for ``standard threshold shift,'' defined in Sec. 62.101 of
the final rule, which are addressed in detail in the preamble
discussion of that section.
[[Page 49617]]
Paragraph (a)(2)(ii) of this section of the final rule also
requires the evaluator of audiograms to determine if there has been a
``reportable hearing loss.'' Under part 50 of MSHA regulations, mine
operators must notify MSHA within ten working days of detection of a
miner's hearing loss. ``Reportable hearing loss'' is defined in
Sec. 62.101 of the final rule as a change in hearing sensitivity for
the worse relative to a miner's baseline audiogram, of an average of 25
dB or more at 2000, 3000, and 4000 Hz in either ear. Several commenters
disagreed with the proposed definition of ``reportable hearing loss,''
and this issue is discussed in detail in the preamble in Sec. 62.101.
Paragraph (a)(3) of this section of the final rule adopts proposed
Sec. 62.160(a)(3), with one addition, and requires the mine operator to
instruct the physician, audiologist, or qualified technician not to
reveal to the mine operator, without the written consent of the miner,
specific findings or diagnoses unrelated to the miner's exposure to
occupational noise or the wearing of hearing protectors. In response to
commenters, the final rule includes qualified technicians among those
who would receive this instruction. Although OSHA's air quality
standards and benzene and lead standards contain similar provisions,
neither MSHA's nor OSHA's noise standard currently includes such a
restriction.
This aspect of the proposal elicited many comments. A number of
commenters opposed the proposed restriction, for a variety of reasons.
Some stated that if the physician or audiologist discovers a condition
that could affect the safety or health of the miner or other miners in
the workplace, the mine operator should be provided with that
information, and the miner should not be permitted to withhold it.
Others believed that if mine operators are required to pay for the
testing, they are entitled to have access to the information. Still
others believe that because mine operators are responsible for
protecting miners against noise-induced hearing loss, all information
relating to the miner's hearing loss, whether occupationally related or
not, should be made available to mine operators or persons employed by
operators to administer hearing conservation programs or who are
responsible for the working conditions and job assignments of
individual miners. On the other hand, one commenter stated that
voluntary audiometric testing results should be treated as confidential
medical information, and not be disclosed to anyone without the miner's
consent.
MSHA has concluded that some protection must be provided to
individual miners' medical information that is not occupationally
related. Accordingly, to safeguard the privacy of individual miners,
the final rule adopts the proposed provision that requires mine
operators to instruct the physician or audiologist conducting the
audiometric test not to reveal to the mine operator information that is
not occupationally related.
Although MSHA agrees that it is conceivable that some non-
occupational medical conditions (such as an inner ear condition that
affects the miner's balance) discovered during an audiometric
examination could have a bearing on a miner's safety at the mine site,
it has concluded that concerns for the miner's privacy outweigh the
mine operator's need for such information. Any greater access to
results of audiometric testing could discourage miners from submitting
to this voluntary testing. In any case, the miner is free to share such
information with the mine operator if he or she chooses to do so.
Other commenters were concerned about the impact the proposed
restriction would have on the ability of mine operators to defend
against hearing loss claims filed under state workers' compensation
laws. These commenters were afraid that the restriction would limit
mine operators' access to relevant information on non-occupationally
related conditions discovered during the course of audiometric testing,
and would therefore prevent them from using this information as a
defense. Nothing in the final rule would prevent a mine operator from
arranging a medical examination for a miner to determine the validity
of a workers' compensation claim. Such an examination would be outside
the purview of this rule and not subject to the limitations imposed
under this section. Additionally, information that is relevant to a
workers' compensation claim may be subject to the discovery process in
civil litigation and may be required to be produced under state law.
The restriction in the final rule would not preclude such disclosure.
One commenter suggested that the final rule should make clear that
physicians and audiologists who are employees of the mine operator have
the same access to test findings and diagnoses as any other physician
or audiologist, even though the company-employed professionals could be
considered to be agents of the mine operator. The commenter believed
that a literal interpretation of this provision would preclude company
physicians or audiologists from either conducting audiometric tests or
evaluating audiograms. MSHA agrees that medical professionals
conducting audiometric testing who are employees of the mine operator
should have the same access to test findings and diagnoses, and are
bound by the same strictures on confidentiality as professionals who
are independently employed. However, MSHA has concluded that
clarification of this interpretation in the preamble is sufficient, and
no specific provision needs to be included in the final rule.
Several commenters pointed out that the proposal would require the
mine operator to instruct the physician or audiologist not to reveal
information to the mine operator, but would not require a qualified
technician performing the audiometric testing to be similarly
instructed. This commenter believed that technicians should be given
the same direction by the mine operator. As stated above, MSHA has
adopted this comment in the final rule for consistency. The expectation
is that the physician, audiologist, or qualified technician will
receive the instruction from the mine operator and will ensure that the
information will be protected.
Under paragraph (a)(4) of Sec. 62.172 of the final rule, which has
been adopted without change from Sec. 62.160(a)(4) of the proposal, the
mine operator must obtain the audiometric test results and the
interpretation of the results from the person evaluating the audiogram
within 30 days of the testing. OSHA's noise standard does not specify a
deadline for the evaluation of audiograms.
Some commenters stated that 30 calendar days may not be sufficient
for a mine operator to obtain audiometric test results from the test
provider. Several commenters expressed concerns about this deadline,
and felt that it would be unrealistic, particularly if a mobile test
van provides the audiometric testing. A number of commenters suggested
the deadline be extended to 60 days. One other commenter believed that
75 days would be appropriate. Other commenters believed it would be
unfair to penalize the mine operator, who has little or no control over
the promptness with which the test provider furnishes test results to
the operator. Several commenters suggested that the final rule require
mine operators to do what they can to obtain test results within 30
days, but should not penalize operators for late results when the delay
is beyond their control. In contrast, one commenter recommended that
the time limit be reduced to 15 days.
[[Page 49618]]
MSHA has determined that a 30-calendar-day time limit for the
evaluation of audiograms is reasonable, and is necessary to prevent
undue delays in the evaluation of the audiogram and in notification of
the miner of the results. Because Sec. 62.175 of the final rule allows
mine operators 10 working days after receipt of test results to notify
a miner of those results, more than 40 days may pass from the date of
an audiometric test until the miner receives notification of the test
results. In those cases where an audiometric retest is appropriate,
miners may not receive their test results more than 100 days after the
initial testing. MSHA has concluded that increasing the deadline to 60
or 75 days would result in unacceptably long delays in miner
notification. Moreover, contrary to the assertions of commenters, MSHA
does not believe that mine operators have little or no control over the
promptness with which test results will be furnished. Under the final
rule mine operators will either directly employ test providers, in
which case meeting the 30-day time frame will be directly within their
control, or contract for this service, in which case they may ensure
that compliance with the 30-day deadline is a requirement of the
contract. Accordingly, MSHA has concluded and the final rule reflects
that the mine operator must obtain the requisite evaluation of an
audiogram within 30 days.
Paragraph (b)(1) of Sec. 62.172 of the final rule, which is adopted
from Sec. 62.160(b)(1) of the proposal, requires the mine operator to
offer an audiometric retest within 30 calendar days of receiving a
determination that an audiogram is invalid, provided any medical
pathology has improved to the point that a valid audiogram may be
obtained. If the results of an annual audiogram demonstrate a standard
threshold shift or a reportable hearing loss, paragraph (b)(2) of this
section allows a mine operator to offer the miner one retest within 30
calendar days of receiving the results. This will allow mine operators
to verify the results of the annual audiogram. The mine operator may
then substitute the results of the retest for the annual audiogram.
These provisions are similar to provisions in OSHA's noise standard,
which permits a retest within 30 days to confirm a standard threshold
shift, but which does not specifically require a retest if the
audiogram is judged to be invalid.
Few comments were received on this aspect of the proposal. One
commenter stated that scheduling miners for a retest can be difficult,
and recommended that the final rule allow 60 days for a mine operator
to offer a miner a retest. One other commenter recommended that MSHA
adopt the provisions in OSHA's standard for audiometric retests if a
standard threshold shift is found.
Under the final rule, audiometric retesting where a miner's initial
audiogram has been determined to be invalid must occur within 30
calendar days, provided that any medical pathology that may have
prevented the taking of a valid audiogram has improved to the point
where a valid retest can be conducted. It should be noted that the 30-
day period does not begin until the medical pathology causing the
problem has improved. The provision in paragraph (b)(2) for a retest
after detection of a standard threshold shift allows the mine operator
to substantiate that the shift has occurred and confirm that the
hearing loss detected is permanent before taking required corrective
actions such as miner retraining and review of the effectiveness of
noise controls at the operator's mine. In the event that the miner
declines to submit to a retest, the 30-day period within which
corrective action must be taken would begin from the date of the
miner's refusal of a retest.
MSHA has concluded that 30 days is a reasonable deadline for
audiometric retesting, recognizing that 30 days may not be sufficient
time for a retest if a mine operator must rely on a mobile test van to
provide the retesting. However, where retesting is necessary, MSHA
believes that it should be conducted as quickly as possible, and the
mine operator may find it necessary to send the miner to the nearest
available testing facility rather than waiting for a mobile test van.
Paragraph (c) of Sec. 62.172, which is adopted unchanged from
proposed Sec. 62.160(c), allows the adjustment of audiometric test
results for the contribution of age-induced hearing loss in determining
whether a standard threshold shift or reportable hearing loss has
occurred. Adjustment of audiometric test results for age-induced
hearing loss is optional under the final rule; however, any such
adjustment must be made to both the baseline and annual audiograms, in
accordance with the procedures set forth in paragraphs (c)(1) through
(c)(3). For each audiometric test frequency, determine from Table 62-3
or 62-4 the age correction values for the miner by: (1) Finding the age
at which the baseline audiogram or revised baseline audiogram was taken
and recording the corresponding values of age corrections at 2000 Hz
through 4000 Hz;
(2) Finding the age at which the most recent audiogram was taken
and recording the corresponding values of age corrections at 2000 Hz
through 4000 Hz; and (3) Subtracting the values found in step (1) from
the value found in step (2). The differences calculated represent that
portion of the change in hearing that may be due to aging. For example:
the miner is a 32-year-old male. The audiometric history for his right
ear is shown in decibels below.
------------------------------------------------------------------------
Audiometric test
frequency (Hz)
Miner's age -----------------------
2000 3000 4000
------------------------------------------------------------------------
26.............................................. 5 5 10
27 *............................................ 0 0 5
28.............................................. 0 0 10
29.............................................. 0 5 15
30.............................................. 5 10 20
31.............................................. 10 20 15
32 *............................................ 10 10 25
------------------------------------------------------------------------
The audiogram at age 27 is considered the baseline since it shows the
best hearing threshold levels. Asterisks have been used to identify the
baseline and most recent audiogram. A threshold shift of 20 dB exists
at 4000 Hz between the audiograms taken at ages 27 and 32. (The
threshold shift is computed by subtracting the hearing threshold at age
27, which was 5, from the hearing threshold at age 32, which is 25). A
retest audiogram has confirmed this shift. The contribution of aging to
this change in hearing may be estimated in the following manner. Go to
Table 62-3 and find the age correction values, in dB, for 4000 Hz at
age 27 and age 32.
------------------------------------------------------------------------
Frequency (Hz)
-----------------------
2000 3000 4000
------------------------------------------------------------------------
Age 32.......................................... 5 7 10
Age 27.......................................... 4 6 7
Difference...................................... 1 1 3
------------------------------------------------------------------------
The difference represents the amount of hearing loss that may be
attributed to aging in the time period between the baseline audiogram
and the most recent audiogram. In this example, the difference at 4000
Hz is 3 dB. This value is subtracted from the hearing level at 4000 Hz,
which in the most recent audiogram is 25, yielding 22 after adjustment.
Then the hearing threshold in the baseline audiogram at 4000 Hz (5) is
subtracted from the adjusted annual audiogram hearing threshold at 4000
Hz (22). Thus the age-corrected threshold shift would be 17 dB (as
opposed to a threshold shift of 20 dB without age correction).
OSHA's noise standard also permits the use of age-induced hearing
loss
[[Page 49619]]
correction factors at the employer's option. OSHA's rationale for
inclusion of these correction factors is that they aid in
distinguishing between occupationally induced and age-induced hearing
loss. This is particularly important because the pattern of hearing
loss due to aging closely resembles that of hearing loss due to noise
exposure.
Many commenters who addressed this issue supported the use of age
correction factors. Some of these commenters believed that failure to
adjust audiometric test results based on a miner's age would result in
inaccurate data, and may indicate that there is a higher incidence of
hearing loss due to workplace noise exposure than actually would be
occurring. Some commenters stated that many older miners would be found
to have a standard threshold shift. As a result, mine operators would
be required to take unnecessary corrective measures at their mines to
address these miners' hearing loss, which may be unrelated to
occupational noise exposure. One commenter stated that adjustment for
age-induced hearing loss is a widely accepted practice, and is
supported by the scientific community and by the relevant scientific
literature. Some commenters opposed the use of age corrections, because
they were concerned that it could interfere with the detection of
noise-induced hearing loss in some miners, and because necessary
corrective actions would not be taken, and the miners' hearing would be
permitted to deteriorate even further.
NIOSH currently recommends that audiograms not be corrected for
age, based on the reasoning that it is inappropriate to apply age
correction factors from a population to an individual. NIOSH maintains
that if a worker's audiogram is to be corrected for age, the hearing
loss of a non-occupational noise-exposed group with the same
demographic characteristics as the worker should be used.
MSHA has concluded that the optional use of age correction factors
is appropriate, and has adopted in the final rule the proposed
provisions that allow it. Such adjustments are consistent with current
scientific practice and with OSHA's noise standard.
MSHA agrees that not all individuals' hearing is affected to the
same degree by age. Additionally, studies have shown that individuals
in environments free from noise exposure display little evidence of
age-induced hearing loss. However, MSHA agrees with the commenters who
stated that failure to allow age correction in the final rule would
result in many miners being found to have incurred standard threshold
shifts, when the primary cause of the shift is the aging process.
The age correction procedures and tables included in the proposal
and adopted in the final rule are those that were used by NIOSH in its
1972 Criteria Document on Occupational Exposure to Noise. Although
there may be slight variations in adjustment at individual frequencies
among similar tables developed by other researchers, the NIOSH age
values are similar to those of other widely accepted and applied age-
induced hearing loss data bases, such as the database of the U.S.
Public Health Service, the data used by Robinson and Burns, and those
of Passchier-Vermeer. The NIOSH data are derived from a highly screened
population, that is, one which excluded individuals with any
significant noise exposure on the job, off the job, or during military
service. Use of a single set of age values will standardize the process
of determining standard threshold shifts nationwide. Proposed Tables
62-3 and 62-4 have been adopted under the same numbers in the final
rule.
Section 62.173 Follow-Up Evaluation When an Audiogram Is Invalid
This section of the final rule has been adopted from Sec. 62.170 of
the proposal, and establishes requirements for a follow-up evaluation
of a miner's hearing if a valid audiogram cannot be obtained because of
a suspected medical pathology caused or aggravated by noise exposure or
the use of hearing protectors. This section also provides that, in the
event that the medical pathology is unrelated to noise exposure or to
the use of hearing protectors, the mine operator must instruct the
physician or audiologist to inform the miner of the need for an
examination. Finally, mine operators must instruct the physician,
audiologist, or qualified technician not to reveal to the mine operator
findings or diagnoses unrelated to the miner's occupational noise
exposure or the wearing of hearing protectors. MSHA's current noise
standards have no provisions that address follow-up evaluations.
Paragraph (a) of Sec. 62.173 of the final rule provides that if a
valid audiogram cannot be obtained due to a suspected medical pathology
of the ear, and the physician or audiologist evaluating the audiogram
believes that the problem was caused or aggravated by the miner's
exposure to noise or wearing of hearing protectors, a miner must be
referred for a clinical-audiological or otological evaluation, as
appropriate, at the mine operator's expense. Section 62.101 of the
final rule defines ``medical pathology'' as ``a condition or disease.''
Several commenters maintained that physicians should not be
included among those who may determine that a miner needs a follow-up
evaluation, because physicians who are not hearing specialists may not
be qualified to determine that a miner needs a follow-up examination.
MSHA has not adopted the suggestion of these commenters in light of the
licensing and ethical standards that apply to physicians. The Agency
expects that physicians will exercise professional judgment in
assessing whether they possess the experience and qualifications to
make the required medical determinations. This issue of the
qualification of physicians is addressed in greater detail in the
preamble discussion of Sec. 62.170.
If the physician or audiologist believes that the suspected
pathology that prevents taking a valid audiogram is related to
occupational noise exposure or to the wearing of hearing protectors,
the final rule requires the mine operator to pay for the miner's
follow-up medical evaluations. Several commenters to the proposed rule
were concerned that this could be read to require the mine operator to
pay for a follow-up examination for an ear infection, if the
audiologist or physician merely ``believes'' that the infection is
aggravated by occupational noise exposure or the wearing of hearing
protectors. These commenters stated that the mine operator should be
required to pay only for treatment of conditions that actually result
from noise exposure that occurs or hearing protectors that are used at
the mine operator's facility.
The final rule reflects MSHA's conclusion that mine operators have
primary responsibility for work-related medical problems. Under the
final rule, if the physician or audiologist determines that the
suspected medical pathology is unrelated to the miner's occupational
noise exposure or to the wearing of hearing protectors, the mine
operator must instruct the medical professional to inform the miner of
the need for an otological examination. The final rule does not require
the mine operator to pay for this examination, which will be at the
miner's expense.
Another commenter suggested that mine operators be required to pay
for follow-up evaluations only if there has been a determination of
significant occupational noise exposure. The final rule does not adopt
this comment, because a determination of the need for a clinical-
audiological or an otological examination under this section should not
be based solely on a miner's noise
[[Page 49620]]
exposure, but should be made after a review of a miner's audiometric
records and a finding of a suspected medical pathology related to
occupational noise exposure or the wearing of hearing protectors. In
some cases information on a miner's noise exposure may be scarce or
nonexistent. Although noise exposure measurements provided by the mine
operator may form part of the basis upon which the qualified reviewer
makes a determination, the final rule does not adopt the commenter's
suggestion that mine operators be required to pay for follow-up
examinations only when the miner has been exposed to significant
occupational noise.
The preamble to the proposal noted that the type of follow-up
evaluation that should be conducted as a result of the suspected
medical pathology (clinical-audiological or otological) depends upon
the specific circumstances in each case. Standards found in the
international community and the U. S. armed forces vary to some degree
regarding certain elements, such as the extent of follow-up
examinations. A clinical-audiological evaluation is generally more
comprehensive, intensive, and accurate than the routine audiometric
testing conducted to identify a hearing loss, and may be warranted if,
for example, an unusually large threshold shift occurs in one year
given relatively low noise exposures. An otological evaluation, on the
other hand, is a medical procedure conducted by a medical specialist
such as an otolaryngologist to identify a medical pathology of the ear,
such as an acoustic neuroma, a type of tumor. Another more common
reason for an otological examination is for the removal of impacted ear
wax, which reduces hearing sensitivity and can be aggravated by the use
of earplug-type hearing protectors. Audiometric testing can indicate
the existence of such medical pathologies.
Making the determinations under this section will not require a
diagnosis by a physician-specialist confirming a medical pathology. The
rule is intended to allow the audiologist or physician authorized to
review the audiograms to make a determination as to whether a follow-up
examination is appropriate-and who pays for it. Accordingly, the word
``suspected'' precedes the words ``medical pathology'' in this section.
Finally, one commenter suggested changing the term ``medical
pathology'' in this paragraph to ``medical condition'', because the
term ``pathology'' implies illness. The final rule does not adopt the
suggestion of this commenter, because the definition of ``medical
pathology'' in Sec. 62.101 of the final rule is not limited to illness,
and encompasses not only a ``disease'' but also a ``condition''
affecting the ear.
Paragraph (b) provides that if the physician or audiologist has
concluded that the suspected medical pathology of the ear which
prevents obtaining a valid audiogram is unrelated to the miner's
exposure to occupational noise or the wearing of hearing protectors,
the mine operator must instruct the physician or audiologist to inform
the miner of the need for an otological evaluation. In such cases, the
final rule imposes no financial obligation on the mine operator.
Paragraph (c) of Sec. 62.173 adopts, with one addition, the
proposed requirement that the mine operator instruct the physician or
audiologist not to reveal to the mine operator any specific findings or
diagnoses unrelated to the miner's exposure to noise or the wearing of
hearing protectors without the written consent of the miner. As under
the similar requirement in Sec. 62.172, commenters suggested adding
qualified technician to the list of persons that the mine operator must
instruct. MSHA has adopted this suggested change in the final rule.
Some commenters were concerned that this restriction would be
counterproductive and harmful to the miner in cases where the miner's
medical condition should be better understood by the mine operator in
order to allow the miner to be more effectively protected on the job.
This aspect of the proposal, which is similar to the restriction in
Sec. 62.172(a)(3) of the final rule, was the subject of several
comments. Some commenters were opposed to the proposed restriction for
a variety of reasons. Some of these commenters stated that if the
physician or audiologist discovers a condition that could affect the
safety or health of the miner in the workplace, the mine operator
should be provided with that information, and the miner should not be
permitted to withhold it. One commenter was concerned about the impact
the proposed restriction would have on the ability of mine operators to
defend against hearing loss claims filed under state workers'
compensation laws. Others maintained that because the mine operator is
responsible for protecting miners against noise-induced hearing loss,
all information relating to the miner's hearing loss, whether
occupationally related or not, should be made available to the mine
operator.
MSHA has concluded that some protection must be given to individual
miners' medical information that is not occupationally related.
Accordingly, to safeguard the privacy of individual miners, the final
rule adopts the proposed provision that requires mine operators to
instruct the physician or audiologist not to reveal to the mine
operator information not occupationally related. A more detailed
discussion of the basis for MSHA's conclusion on this issue can be
found in the preamble under Sec. 62.172(a)(3).
Section 62.174 Follow-Up Corrective Measures When a Standard Threshold
Shift Is Detected
This section of the final rule, which adopts the requirements of
proposed Sec. 62.180, establishes the corrective measures that must be
taken by a mine operator when a miner is determined to have incurred a
standard threshold shift in hearing sensitivity. This section provides
that, unless a physician or audiologist determines that the standard
threshold shift is neither work-related nor aggravated by occupational
noise exposure, mine operators must take specified corrective actions
within 30 calendar days after receiving evidence or confirmation of a
standard threshold shift. ``Standard threshold shift'' is defined in
Sec. 62.101 of the final rule as a change in hearing sensitivity for
the worse relative to the miner's baseline audiogram (or revised
baseline audiogram) of an average of 10 dB or more at 2000, 3000, and
4000 Hz in either ear.
The corrective actions that mine operators are required to take
under Sec. 62.174 of the final rule when a miner experiences a standard
threshold shift include: Retraining the affected miner in accordance
with Sec. 62.180 of the final rule, providing the miner with the
opportunity to select a different hearing protector, and reviewing the
effectiveness of any engineering and administrative controls to
identify and correct any deficiencies.
A number of commenters supported the need for intervention by the
mine operator when a miner has experienced a standard threshold shift.
Several of these commenters stated that it should not matter whether or
not a standard threshold shift is work-related, and that intervention
should be required in any case to prevent further hearing loss. One of
these commenters stated that it is probably not realistic to believe
that the mining industry can identify outside causes of hearing loss.
Another commenter was of the opinion that miners whose audiograms
indicate such a degree of hearing loss should still be provided with
information and training on how they can protect themselves. Still
another commenter stated that the final rule should require additional
[[Page 49621]]
actions, including examination of the noise exposure of the affected
miner or of other miners with similar occupations. This commenter
strongly supported a requirement that the mine operator investigate the
cause of the miner's standard threshold shift.
One commenter believed that effective training and audiometric
testing would make corrective measures after the detection of a
standard threshold shift unnecessary. This commenter added that miners
should be encouraged to take responsibility for their own health.
Several other commenters stated that the proposed requirements for
corrective action underscored a need for mandatory participation by
miners in audiometric testing. These commenters maintained that an
effective hearing conservation program must require miners to submit to
such tests.
MSHA has concluded that it is essential that mine operators be
required to take certain corrective measures to prevent further
deterioration of miners' hearing sensitivity after a standard threshold
shift has been detected. A hearing loss of 10 dB is sufficiently
significant to warrant intervention by a mine operator, unless it is
determined the loss is not work-related. If miners are experiencing
that level of occupationally related noise-induced hearing loss, as
determined by a physician or audiologist, it is a clear indication that
the noise controls in place at the work site have been ineffective. In
such situations further action is appropriate to determine why the
miner has not been adequately protected.
Paragraph (a) of Sec. 62.174 of the final rule requires that the
miner be retrained, which includes the instruction required by
Sec. 62.180 of the final rule, under which training must address such
topics as the effects of noise on hearing, the value and effective use
of hearing protectors, the operator's and miner's respective tasks in
maintaining mine noise controls, and the value of audiometric testing.
Commenters on this aspect of the proposal generally supported the
training requirement.
As indicated in the preamble to the proposal, if the noise controls
in place are effective--including the training--this hearing loss
should not be occurring. Providing the miner with retraining after the
miner has experienced a standard threshold shift is intended to ensure
that the miner is not inadvertently being overexposed to noise because
of a lack of awareness about effective use of noise controls or hearing
protectors. This retraining may also emphasize to the miner the
importance of regular audiometric testing, to ensure that the hearing
loss does not progress. Also as indicated in the preamble to the
proposal, the required training may be conducted in conjunction with
annual refresher training under 30 CFR Part 48, but only if the
training will be conducted within 30 days of the detection of the
standard threshold shift, the time frame established in this section.
Paragraph (b), like the proposal, requires the mine operator to
provide the miner with an opportunity to select a hearing protector, or
a different hearing protector if the miner has previously selected a
hearing protector, from among those offered by the mine operator in
accordance with Sec. 62.160. Several commenters advocated the inclusion
of the additional requirement that the hearing protector be checked to
ensure that it is in good condition, and replaced if necessary. These
commenters also recommended that miners should be encouraged to select
a hearing protector providing greater noise reduction.
The final rule, like the proposal, allows miners to select their
own hearing protectors. The effectiveness of any hearing protector
depends on a number of factors, only one of which is its noise
reduction rating value. Even though a miner may not select the hearing
protector with the highest noise reduction rating, factors such as
comfort, fit, and personal preference are critical in ensuring that the
miner will fully utilize this essential piece of personal protective
equipment. Moreover, there is no standardized objective method to
determine the degree of protection a given hearing protector will
provide a miner. MSHA has therefore determined that requiring that
miners be encouraged to select a hearing protector based primarily or
exclusively on the protector's noise reduction rating value would not
be well advised, and this comment has therefore not been adopted in the
final rule. The final rule also does not adopt commenters' suggestions
that mine operators be required to check the fit and condition of the
hearing protector and replace it, if necessary, because these concerns
are already addressed in other sections of the final rule. As
Sec. 62.180 of the final rule requires that miner training address the
care, fitting, and use of hearing protectors, miners will be trained to
evaluate the condition of their hearing protectors and notify the mine
operator when the condition of the protector has deteriorated and needs
to be replaced. The issue of selection and effectiveness of hearing
protectors is addressed in greater detail in the preamble discussion of
Sec. 62.160.
Several commenters supported the addition of a requirement that the
miner use a hearing protector and the mine operator enforce its use
when a standard threshold shift is detected. The final rule also
requires that the mine operator provide and ensure that miners wear
hearing protectors under certain conditions, including when the miner
incurs a standard threshold shift and is exposed to noise at or above
the action level. A more detailed discussion of mandatory use of
hearing protectors is included under Sec. 62.130 of the preamble, which
addresses the permissible exposure level.
Paragraph (c) of this section of the final rule requires the mine
operator to review the effectiveness of any engineering and
administrative noise controls, in order to identify and correct any
deficiencies. The implementation and maintenance of engineering and
administrative noise controls when miners are subjected to noise
exposures above the permissible exposure level is the primary method
for reducing miners' noise exposure and their risk of hearing loss.
Because ineffective engineering and administrative controls may be the
primary cause of a miner's standard threshold shift, the final rule
requires the mine operator to review the effectiveness of existing
controls and update or modify them to enhance the protection provided
to miners. OSHA's existing noise standard does not require such a
review when a standard threshold shift is detected.
Some commenters supported the proposed review of engineering and
administrative controls when a miner experiences a standard threshold
shift. However, several commenters noted that a mine operator should
not be required to review the effectiveness of engineering and
administrative noise controls if the standard threshold shift occurs in
a single miner and can be positively attributed to the inaction of that
miner.
This comment has not been adopted in the final rule. Mine operators
are responsible for protecting miners from overexposures to noise at
the mine site. The mine operator must determine which are the best and
most protective controls for the particular operation. The degree to
which the noise controls that have been implemented rely on the actions
of individuals may have some bearing on how well the controls work.
Effective engineering noise controls protect the miner without the need
for the miner's active participation. If the controls in place rely too
heavily on the participation of a miner and have
[[Page 49622]]
proven to be inadequate (as evidenced by the detection of a standard
threshold shift), a prudent mine operator will explore implementation
of engineering controls that will be effective regardless of the
miner's actions. The mine operator determines working conditions at the
mine site and is responsible for ensuring the design, implementation,
and use of effective controls to protect miners from overexposure to
noise and resulting hearing loss.
Although the proposed rule would not have provided for the transfer
of a miner with a diagnosed occupational hearing loss to a low-noise
work environment, MSHA did solicit comments on whether a miner transfer
provision was necessary. Some commenters stated that it would not be
appropriate to include a miner transfer provision in the final rule,
arguing that miners could manipulate audiogram results (for example, by
listening to loud music prior to the test) in an attempt to force mine
operators to move them to different, more desirable jobs. Other
commenters supported the concept of a miner transfer provision, arguing
that this is appropriate when other efforts to halt the progression of
the miner's hearing loss have failed and that miners who were
transferred should suffer no loss in wages or benefits as a result,
similar to the provisions in MSHA's part 90 regulations for coal miners
who have evidence of black lung disease.
The preamble to the proposed rule suggested that a miner transfer
program would be extremely complex for mine operators to administer,
and may be quite infeasible for the metal and nonmetal mining industry.
The majority of metal and nonmetal mines are smaller mines, many of
which would be unable to rotate miners with hearing loss to other, less
noisy assignments on a long-term basis. Although MSHA encourages mine
operators to transfer miners who have incurred a hearing impairment to
jobs with reduced noise exposure, it has concluded that a miner
transfer provision is not feasible at most small mining operations, due
to the small number of employees and the limited number of positions
with low noise exposure to which miners with hearing loss could be
transferred. Because of the significant feasibility problems presented
by mandatory miner transfer and the lack of consensus in the mining
community on the advisability of a transfer program, the final rule
does not adopt a miner transfer provision.
Section 62.175 Notification of Results; Reporting Requirements
This section of the final rule is identical to Sec. 62.190 of the
proposal, providing for miner notification of audiometric test findings
and for notification to MSHA of any instances of ``reportable hearing
loss,'' as defined in Sec. 62.101 of the final rule.
Paragraph (a) of this section of the final rule requires that mine
operators notify the miner in writing of the results of an audiogram or
a follow-up evaluation within 10 working days of receiving the results.
There are no existing MSHA regulations that impose such a requirement.
MSHA received no comments opposing a miner notification
requirement, although several commenters believed that mine operators
should be required to notify a miner of test results only when the
results indicate a significant shift in the miner's hearing level,
consistent with OSHA requirements. These commenters believed that miner
notification was not warranted if the audiometric test indicated no
additional hearing loss.
Commenters disagreed on the length of the period within which such
notification should occur. Several commenters recommended that MSHA
adopt the provision in OSHA's noise standard that requires employee
notification within 21 days. Other commenters recommended a 15-day
deadline, while still others believed that a 30-day deadline was
appropriate. The commenters who supported a longer period believed that
10 days was insufficient to allow mine operators to review the
audiograms and to provide the required notification, particularly if
large numbers of miner audiograms were conducted and processed at the
same time. One commenter stated that miners should be informed of a
standard threshold shift at the time of the test, and provided with the
results of audiograms within 5 days rather than 10.
Although no commenter specifically objected to the requirement that
the miner notification be in writing, several commenters stated that
the method of notification should be left to the discretion of the mine
operator. Another commenter recommended that mine operators notify
miners in a timely manner and also share the results with other miners
during annual refresher training, apparently based on the belief that
if miners hear of co-workers' hearing losses, it might serve to
reinforce their own understanding of the need for noise controls and
the importance of using hearing protectors.
After considering the comments, MSHA has concluded that informing
miners of the results of their audiometric tests in a timely manner is
critical to the effectiveness of a hearing conservation program.
Immediate feedback to the miner at the completion of the test provides
the greatest benefit, because that is the point at which miners
typically have the greatest interest in information on the effects of
noise on their hearing, and are more likely to take action, such as
wearing hearing protectors conscientiously; stringently complying with
administrative noise controls; or continuing to submit to audiometric
testing.
The Agency realizes that it may not be practical to inform miners
immediately of the results of their audiometric tests. However, because
of the importance of the information, it is necessary to establish a
maximum time frame for mine operators to inform miners of the
audiometric test findings and results. Therefore, the final rule adopts
the requirements of the proposed rule and allows mine operators up to
10 working days after the receipt of test results to inform the miner.
This means that mine operators will have up to two weeks to make this
notification, which is a sufficient time frame for this notification.
MSHA has also concluded that it is appropriate to require written
notification to miners of their test results. Important that miners are
made aware of their test results, and written notice minimizes the risk
of misunderstanding on the part of miners. Some commenters stated that
notification is necessary only when a standard threshold shift has
occurred, but MSHA believes that notification of good results serves to
reinforce effective practices and strengthens the effects of a hearing
conservation program.
Because of the confidentiality of audiometric test results, it
would be inappropriate, as suggested by a commenter, for the final rule
to require a mine operator to share an individual miner's test results
with other miners. The final rule therefore does not adopt this
comment.
Paragraph (a)(1) of this section adopts without change
Sec. 62.190(a)(1) of the proposal, and requires that the mine operator
inform the miner of the results and interpretation of the audiometric
test, including any finding of a standard threshold shift or reportable
hearing loss. This differs from OSHA's noise standard, which only
requires notification of a confirmed standard threshold shift. The
requirements of this paragraph ensure that miners receive timely
information of the results of their audiometric tests, and can take
appropriate actions in conjunction with the mine operator, in order to
reduce
[[Page 49623]]
further occupational noise-induced hearing loss.
Paragraph (a)(2) of Sec. 62.175, like the proposal, requires that
the mine operator notify the miner of the need and reasons for any
further testing or evaluation, if applicable.
One commenter stated that a mine operator could not notify miners
of the reason for further testing or evaluation, because under the
proposal, adopted in Sec. 62.173(c) of the final rule, mine operators
would not be told of findings or diagnoses when the condition diagnosed
is not work-related. MSHA has concluded that this limitation does not
present an obstacle to mine operators notifying miners of the need and
reasons for further testing or evaluation. If the problem encountered
is occupationally related, the mine operator will be informed of the
specific reasons why a follow-up is needed. If the problem is not
occupationally related, the mine operator will be informed only that a
follow-up is warranted and must pass that information on to the miner
as part of the notification required under this section. MSHA expects
that in most if not all cases miners will already be aware of both the
need and reasons why a follow-up is recommended, because the person
performing the audiometric tests will convey this information to them
during the course of the test. Notification by the mine operator will
reinforce any information that may have been provided to the miner
during the test procedure.
Paragraph (b) of Sec. 62.175 of the final rule, like the proposal,
requires mine operators to inform MSHA when a miner has incurred a
reportable hearing loss as defined in part 62, unless the physician or
audiologist has determined the loss is neither work-related nor
aggravated by occupational noise exposure. This provision parallels
existing requirements in part 50, which require mine operators to
report a miner's hearing loss whenever a physician determines that it
is work-related, or whenever an award of compensation is made. Section
50.20-6 specifically includes noise-induced hearing loss as an example
of a reportable occupational illness. However, Sec. 62.101 of the final
rule now provides an explicit definition of ``reportable hearing
loss,'' in order to clarify mine operators' compliance responsibilities
and promote the development of improved data on hearing loss in the
mining community.
Section 62.101 of the final rule adopts the proposed definition of
``reportable hearing loss'' as a change in hearing sensitivity for the
worse, relative to the miner's baseline audiogram, of an average of 25
dB or more at 2000, 3000, and 4000 Hz in either ear. The issue of the
definition of reportable hearing loss is discussed in the preamble
under Sec. 62.101.
An important goal of the final rule is to clarify the level of
hearing loss that is reportable to MSHA under part 50. MSHA
acknowledges that its current reporting requirements have resulted in
inconsistent reporting; some mine operators have reported even small
hearing losses, while other operators only report a miner's hearing
loss when the miner has received an award of compensation. In other
cases, mine operators have not reported a miner's hearing loss even
when an award of compensation was made because the miner had retired.
Inconsistent reporting of miners' hearing loss may also stem from the
fact that the definition of compensable hearing loss under workers'
compensation laws varies widely from state to state. For these reasons,
MSHA had concluded that its miner hearing loss data under part 50 tends
to underestimate the prevalence or degree of hearing loss in the mining
industry.
Providing a specific definition in the final rule for ``reportable
hearing loss'' as it is used under part 50 is intended to eliminate
exclusive reliance on workers' compensation awards as a criterion for
defining when noise-induced hearing loss must be reported.
Nevertheless, part 50 will still require that mine operators report to
MSHA hearing loss for which an award of compensation has been made if
the hearing loss has not been previously reported. Two examples of such
cases are: (1) If the miner incurred the hearing loss before the
current mine operator conducted the baseline or pre-employment
audiogram and subsequent testing did not measure a reportable loss; and
(2) if the miner has not been in a hearing conservation program or has
not received an audiometric test while employed by the mine operator.
In determining what degree of occupational hearing loss should be
reportable under part 50, MSHA gave serious consideration to the fact
that a hearing loss of 25 dB diminishes the quality of life. The
hearing loss that is reportable under the final rule, although not
equal to material impairment, is substantial enough to diminish the
quality of life, and it provides a reliable indication of the
effectiveness of the existing action level and permissible exposure
level.
Several commenters expressed support for the proposed provision,
which is adopted unchanged in this section of the final rule, that a
mine operator is not required to report a miner's hearing loss to MSHA
if a physician or audiologist has determined that the loss is neither
work-related nor aggravated by occupational noise exposure. However,
some commenters advocated that any hearing loss be presumed to be non-
occupationally related, and that the final rule should require the
physician or audiologist to determine definitively that the hearing
loss is work-related before the hearing loss would be reportable. These
commenters objected to the fact that the proposal seemed to presume
that any hearing loss detected would be both noise-induced and work-
related.
The final rule reflects MSHA's determination that it is reasonable
to place the responsibility on the physician or audiologist to
determine when a hearing loss is unrelated to the miner's occupational
exposure to noise or to the wearing of hearing protectors. Although in
some cases it may not be easy to determine whether an identified
hearing loss is work-related or not, the final rule follows the
approach of the proposal that the loss would be reportable in the
absence of evidence that the hearing loss is not work-related. MSHA has
concluded that this approach is the most protective for miners, and has
adopted it in the final rule.
Several commenters stated that the rule is unclear regarding who
would be responsible for reporting a loss when a miner has been
employed by several operators. MSHA specifically solicited comments in
the proposal on how to capture data on work-related noise-induced
hearing loss that is not discovered until after the miner's employment
is terminated, or that the miner had accumulated from work with several
employers. Commenters did not provide any data, information, or
suggestions. The final rule requires the mine operator currently
employing the affected miner to report the hearing loss no matter where
the miner may have incurred the loss, provided it has not been
previously reported.
The final rule does not require that mine operators report the same
``reportable hearing loss'' to MSHA each year that the miner works at
the mine. An additional report to MSHA under part 50 of a hearing loss
involving the same miner is required only if the miner has incurred an
additional 25-dB shift (50-dB shift from the original baseline).
However, each ear should be treated independently in terms of reporting
hearing loss, unless the reportable loss occurs in both ears during a
particular year. Although not specifically required in the final rule,
MSHA anticipates that
[[Page 49624]]
mine operators will report under part 50 the actual average hearing
loss, the ear(s) in which the reportable loss occurred, and whether the
audiograms were corrected for age-induced hearing loss.
Section 62.180 Training
This section establishes specific requirements for training miners
under the final rule. These requirements are very similar to
requirements proposed under Secs. 62.120(b)(1) and 62.130. Under the
final rule, training of miners is one of the elements of a hearing
conservation program. Mine operators are required to enroll miners in
hearing conservation programs under Sec. 62.120, and to provide
training under Sec. 62.180 to miners whose noise exposure equals or
exceeds the action level under Sec. 62.120. Miners are also required
under Sec. 62.160(a)(1) to be trained before they select hearing
protectors. Retraining the miner, including the instruction required
under this section, is also required under Sec. 62.174(a) when the
miner is determined to have experienced a standard threshold shift.
Section 62.180(a) requires that mine operators provide miners with
initial training under this section within 30 days of their enrollment
in a hearing conservation program. Retraining at least every 12 months
thereafter must be provided if a miner's exposure continues to equal or
exceed the action level under Sec. 62.120. The proposal would have
required that mine operators provide a miner with initial training at
the time that the miner's exposure exceeded the action level. In
response to commenters who were concerned that the proposal did not set
a deadline for such training, the final rule requires that initial
training be conducted within 30 days of a miner's enrollment in the
hearing conservation program. OSHA's noise standard includes training
requirements that are similar to those in the final rule.
Paragraphs (a)(1) through (a)(7) of Sec. 62.180 of the final rule,
like Sec. 62.130(a) of the proposal, establish specific requirements
for the training and retraining of miners. Under the final rule, the
mine operator must provide the miner with instruction in the areas of:
the effects of noise on hearing; the purpose and value of wearing
hearing protectors; the advantages and disadvantages of the hearing
protectors to be offered; the care, fitting, and use of the hearing
protector worn by the miner, and the various types of hearing
protectors offered by the mine operator; the general requirements of
part 62; the mine operator's and miner's respective tasks in
maintaining mine noise controls; and the purpose and value of
audiometric testing and a summary of the procedures. Few commenters
specifically addressed the topics in the noise training program.
However, several commenters stated that it was important to stress the
selection, fitting, use, and limitations of hearing protectors.
Although all commenters appeared to support the concept of training
miners on noise-related topics, they disagreed about whether a separate
training requirement was warranted. Some commenters believed that
training miners under this part was unnecessary because miners are
already required to receive training under existing MSHA regulations in
part 48, which require regular training of miners on a variety of
safety-and health-related topics, including the purpose of taking noise
measurements. Some of these commenters were concerned that the training
requirements under this part would create additional recordkeeping
requirements for mine operators and would not serve any purpose, and
they opposed adding additional training requirements under this part.
Other commenters stated that there is not enough time to cover all
the topics required under part 48 training, and therefore separate
training under this part was appropriate, to ensure that miners were
well informed about the hazards of noise and how to ensure that they
are adequately protected. Some of these commenters supported training
on work-related noise hazards as well as proper fitting of hearing
protectors. They argued that miners need training to make them aware of
the damage acoustical energy can do to hearing, and that the proposed
rule seemed to suggest that there was no need to train workers until
they have been enrolled in a hearing conservation program. These
commenters advocated training as a preventive measure rather than as
after-the-fact treatment.
In the preamble to the proposed rule, MSHA stated that there is
considerable precedent for requiring training as part of hearing
conservation programs. As indicated in the preamble, Suter (1986)
states, ``Workers who understand the mechanism of hearing and how it is
lost will be more motivated to protect themselves.'' Other researchers
concur with this opinion (Wright, 1980; Royster et al., 1982).
Moreover, the first line of defense against risks in mining has always
been training. Accordingly, the final rule provides for annual
instruction to enhance awareness of noise risks, operator requirements,
and available controls. This training is required for any miner whose
noise exposure is at or above the action level, an exposure which MSHA
has identified to be hazardous.
MSHA has determined that specialized training on the hazards of
noise and the importance of hearing conservation is necessary because,
as several commenters pointed out, part 48 training typically does not
routinely include detailed training on noise and hearing loss. One
reason for this, as commenters also pointed out, is that there are a
number of safety and health topics required to be covered under part 48
in a relatively short period of time. This does not allow the type of
in-depth training on a narrow topic that is contemplated under this
final rule.
Several commenters took issue with the proposed requirement that
the training be provided ``at the time'' that the miner's noise
exposure exceeds the action level. These commenters stated that the
language should be modified to allow the mine operator more flexibility
regarding how and when training is conducted. Some commenters
recommended one week, while others suggested that mine operators be
allowed 30 days to satisfy this requirement, in order to accommodate
varying shift schedules and to develop and conduct an effective
training program. One commenter recommended that the final rule specify
at least one hour of initial training be given and at least 30 minutes
of annual retraining be given.
MSHA agrees that the language of the proposed rule could be read to
allow mine operators little time to provide training under this part,
and the final rule allows mine operators 30 days to provide the
training after a miner has been enrolled in a hearing conservation
program. Under Sec. 62.120 of the final rule, mine operators must
enroll a miner in a hearing conservation program when the miner's noise
exposure equals or exceeds the action level. This time frame will
ensure that miners receive the necessary training in a timely manner,
while at the same time providing mine operators with a reasonable
amount of time to provide the training.
The final rule does not provide detailed requirements for the
training provided by the mine operator. Instead, like other
performance-oriented aspects of this final rule, mine operators have
the flexibility under this section to determine how best to provide the
training as well as which programs are best suited to conditions at
their mines. The final rule requires that certain topics be covered by
this training, but does not specify how long the training must last nor
what qualifications the
[[Page 49625]]
training instructors must have. Unlike part 48, the final rule does not
require MSHA approval of the mine operator's training plan. However,
mine operators may satisfy the requirements of the final rule and part
48 with the same training, provided that training complies with both
sets of requirements.
MSHA intends that the training required under the final rule
address the advantages and disadvantages of different types of hearing
protectors, including earmuffs, earplugs, and canal caps as they relate
to the needs of the miner and the specific conditions at the mine. In
addition, the mine operator should discuss the specific advantages and
disadvantages of any special hearing protectors offered.
MSHA recommends that mine operators tailor the training provided
under the final rule to the operations at their mines, and may choose
to emphasize certain topics more than others. Although the final rule
provides a basic framework for minimum areas of instruction, the
training requirements provided here are intended to be performance-
oriented and allow for training to be tailored to the individual mine's
circumstances or to individual needs.
Effective training of miners serves to enlist miner participation
in hearing conservation, which is critically important for proper use
of hearing protectors and compliance with applicable administrative
noise controls. Effective training of miners also helps to ensure that
miners will submit to regular audiometric testing, which is completely
voluntary on the part of miners under the final rule. Studies have
shown a correlation between instruction and the amount of protection
afforded a miner by the use of hearing protectors. These include Merry
et al. (1992), Park and Casali (1991), Barham et al. (1989), and Casali
and Lam (1986).
Section 62.180(b) of the final rule adopts the proposed requirement
that the mine operator certify the date and type of training given each
miner and maintain the miner's most recent certification for as long as
the miner is enrolled in the hearing conservation program and for at
least 6 months thereafter. The final rule does not adopt the proposed
requirement that the person conducting the training sign the
certification, nor that the certification be maintained at the mine
site.
A few commenters recommended that the miner be required to sign the
training certificate. This comment has not been adopted in the final
rule. MSHA does not believe that requiring the miner to sign a
certificate furthers the goal of providing quality training. This is
appropriate, given the fact that the mine operator is ultimately
responsible for providing adequate training to miners under this final
rule. For the same reason, the proposed requirement that the training
provider sign the certification has not been adopted.
Some commenters strongly urged that the final rule allow training
certification to be maintained at locations other than the mine site,
since it may be more efficient for some mine operators to store records
at a central location. MSHA agrees, particularly in light of the fact
that electronic records are becoming more common in the mining industry
and may be stored on computer at centralized locations. The final rule
therefore allows mine operators to store training certifications at a
location other than the mine site. However, they must be stored in
sufficient proximity to the mine to be produced for an MSHA inspector
within a relatively short period of time. MSHA expects that in most
cases this will be no longer than one business day.
Mine operators must retain the most recent training certification
for as long as a miner is in the hearing conservation program and for
at least 6 months thereafter. There were only a few comments on this
issue. One commenter suggested that the training records should be
maintained for 12 months, rather than 6 months, beyond the miner's
enrollment in a hearing conservation program, but did not explain why
that would be preferable.
The final rule adopts the proposed requirement that training
records be kept as long as the miner is in the hearing conservation
program and for at least 6 months thereafter. As stated in the proposed
preamble, the retention period is short and not burdensome--only the
most recent certifications must be retained and only for 6 months after
the miner's enrollment in the hearing conservation program has ended.
These records will serve to allow MSHA inspectors to verify that the
required training has been provided.
Section 62.190 Records
The requirements of proposed Secs. 62.200 and 62.210 are combined
in Sec. 62.190 of the final rule, and address access to and transfer of
records required to be kept under this rule. The final rule defines
``access'' as the right to examine and copy records. MSHA's final rule
is essentially the same as OSHA's requirements.
Under paragraph (a), as in the proposal, the mine operator must
provide authorized representatives of the Secretaries of Labor and
Health and Human Services with access to all records required under
this part. Several commenters stated that confidential medical records
should be accessible to government agencies only with the written
consent of the miner. MSHA has a statutory right to have access to
records, including medical records. Section 103(h) of the Federal Mine
Safety and Health Act of 1977 (Mine Act) provides that:
In addition to such records as are specifically required by this
Act, every operator of a coal or other mine shall establish and
maintain such records, make such reports, and provide such
information, as the Secretary or the Secretary of Health, Education,
and Welfare [now Health and Human Services] may reasonably require
from time to time to enable him to perform his functions under this
Act * * *
The Agency believes that access to medical records is essential; the
records will be valuable in enforcement of the final rule, will be
useful in research into the effects of occupational noise exposure, and
will help to evaluate the effectiveness of hearing conservation
programs.
Another commenter noted that the preamble stated that mine
operators would have to provide authorized representatives of the
Secretaries with immediate access to all records required under this
part. It was not MSHA's intent that records be provided immediately to
authorized representatives of the Secretaries. MSHA agrees that
requiring immediate access to records to authorized representatives of
the Secretaries might be too restrictive or burdensome on the mine
operator. Although the preamble to the proposal contained the term
``immediate,'' the final rule does not. Following current practice,
MSHA intends that authorized representatives of the Secretaries have
access to records within a reasonable amount of time that does not
hinder the authorized representatives' conduct of business. In most
cases MSHA expects that this will be no longer than one business day.
MSHA solicited comment on what actions would be required, if any,
to facilitate the maintenance of records in electronic form by those
mine operators who desire to do so, while ensuring access in accordance
with these requirements. The Agency received several comments
supporting electronic storage of records, but no specifics regarding
actions required to facilitate the maintenance of the records in
electronic form.
As in the proposal, paragraph (a) of the final rule also provides
that, upon written request, the mine operator must
[[Page 49626]]
provide, within 15 calendar days of the request, access to records to
miners, former miners, miners' designees, and representatives of
miners. The first copy must be provided at no cost, and any additional
copies at reasonable cost.
Several commenters supported the provisions of access and transfer
of records, but suggested that MSHA have a separate standard, as OSHA
does. The provisions in this final rule are similar to those in other
health standards proposed in recent years by MSHA and are similar to
OSHA's. MSHA and NIOSH have statutory rights to access of records, but
since MSHA does not have generic recordkeeping and access requirements,
including recordkeeping and retention requirements in the substantive
noise regulation will facilitate compliance. This will provide the
regulated community with better clarity regarding applicable
requirements.
Paragraph (a)(1) of this section of the final rule remains
relatively unchanged from the proposal and provides that a miner, or a
miner's designee with the miner's written consent, has access to all
the records that the mine operator is required to maintain for that
miner under this part. Several commenters asked whether the term
``miner's designated representative'' used in Sec. 62.200(a)(1) of the
proposal referred to the representative designated by two or more
miners under part 40 of MSHA's regulations. In fact, the term ``miner's
designated representative'' used in Sec. 62.200(a)(1) of the proposal
was intended to refer to a representative specifically designated by
the miner to have access to records. MSHA agrees that the terms used in
the proposed rule are imprecise; the final rule now substitutes the
term ``miner's designee'' in paragraph (a)(1) for ``miner's designated
representative.'' The term ``miner's designee'' has also been defined
in Sec. 62.101 of the final rule as ``an individual or organization to
whom a miner gives written authorization to exercise a right of access
to records.'' These changes are intended to make clear that the
``miner's designee'' referred to in this section is not a
representative of miners designated under part 40.
Paragraph (a)(2) clarifies that the miners' representative referred
to is the representative designated under part 40 of the regulations.
Section 62.200(a)(2) of the proposal used the ambiguous term ``miners'
representative'' and left doubt in some commenters' minds as to whether
this was the miners' representatives under part 40. Commenters
expressed concern that although the Mine Act gave the part 40 miners'
representative access only to training records and exposure records,
not to confidential medical records, the proposed rule language was
unclear on this distinction. Paragraph (a)(2) of this section of the
final rule clarifies the intent of the proposed rule that miners'
representatives designated under part 40 have access to training
certifications compiled in accordance with Sec. 62.180(b) of the final
rule, and to notices of exposure determinations in accordance with
Sec. 62.110(d). Paragraph (a)(2) does not provide for access to medical
records by the part 40 miners' representative. This is consistent with
the requirements of the Mine Act, and responds to commenters who were
concerned about maintaining the confidentiality of miners' medical
records.
The final rule does not adopt the provision in proposed
Sec. 62.200(a)(1) that would have provided former miners with access to
all records that the mine operator would be required to maintain under
part 62. Instead, the final rule provides that any former miner may
have access to records which indicate his or her own noise exposures.
This revision results from MSHA's recognition that the Mine Act gives
former miners limited access to records. Section 103(c) of the Mine Act
explicitly provides that ``[s]uch regulations [those dealing with toxic
substances and harmful physical agents] shall also make appropriate
provisions for each miner or former miner to have access to such
records as will indicate his own exposure to toxic materials or harmful
physical agents.'' Paragraph (a)(3) has therefore been added to the
final rule to make clear that a former miner may have access to those
records which indicate his or her own noise exposures, but not to other
records that are required to be kept by the mine operator under this
part, as would have been required under the proposal.
One commenter stated that the operator should not be responsible
for providing access to records for anyone other than the affected
employee unless such employee is totally incapacitated, arguing that
review of the preamble and the section-by-section analysis provides no
rationale for including persons other than the employee to have access
to records. MSHA has determined, however, that miners should have the
right to designate someone to access records on their behalf, if they
so desire. For example, a miner who is ill can authorize a designee
(who may be a family member) to retrieve a copy of his or her records.
Several commenters stated that records should not be directly
accessible to any private organizations. Under the final rule, a
private organization may only have access if a miner selects the
organization as his or her designee. In that case, the organization
would have access as the miner's designee to all records required to be
kept under this part for that individual miner.
One commenter maintained that the miner's designee should not be
required to have written permission to see his or her records when no
other person with access is required to have it. The commenter argues
further that if this is due to the confidentiality of medical records,
then anyone should be required to have the written permission of the
miner, including MSHA and NIOSH. However, these agencies have a
statutory right to access to records and do not need the written
consent of the miner, but a designee does not and would therefore need
written authorization to access records that may contain personal,
private information.
Paragraph (a)(2) requires that any representative of miners
designated under part 40 of this title must have access to noise
training certifications required under Sec. 62.180(b) as well as any
notice of exposure determination in accordance with Sec. 62.110(d) of
this part for the miners he or she represents. Several commenters
stated that the miners' representative should not have access to
miners' records unless the miner has given written consent. One
commenter stated that MSHA should change this section to provide access
only to the individual miner involved. Several commenters stated that
MSHA should clarify that the miners' representative will only have
access to the training certificate.
MSHA intends that the miners' representative have access to
training certifications and exposure determination records for miners
they represent, without the written consent of individual miners.
Providing access to training certifications is consistent with the
Agency's part 48 training regulations at Secs. 48.9 and 48.29, which
require training certificates for each miner to be available for
inspection by the miners' representative. Further, section 103(c) of
the Mine Act states:
The Secretary, in cooperation with the Secretary of Health,
Education, and Welfare, [now Health and Human Services] shall issue
regulations requiring operators to maintain accurate records of
employee exposures to potentially toxic materials or harmful
physical agents which are required to be monitored or measured under
any applicable mandatory health or safety standard promulgated under
this Act. Such regulations shall provide miners or their
representatives with an opportunity to observe such
[[Page 49627]]
monitoring or measuring, and to have access to the records thereof *
* *
The final rule does not adopt proposed paragraph (b) of this
section, which would have required an operator, upon termination of a
miner's employment, to provide the miner (at no cost) a copy of all
records that the operator is required to maintain for that individual
miner under this part. The majority of commenters stated that it would
be unduly burdensome to supply records to all terminated employees,
that the provision was redundant with paragraph (c), and that records
should only be provided to those employees who provide a written
request for them. MSHA agrees that mine operators should not have to
provide copies of records to miners unless requested to do so.
Paragraph (c) of this section of the final rule, therefore, like the
proposal, allows persons who have access to records to request a copy
of all records from the mine operator. MSHA believes that this
requirement will provide miners necessary information about their
health. Proposed paragraph (b) has therefore not been adopted in the
final rule.
Paragraph (a)(3), which is identical to proposed 62.200(c), states
that when a person with access to records requests a copy of a record,
the first copy must be provided without cost to that person, and any
additional copies requested by that person must be provided at
reasonable cost. Several commenters suggested that MSHA define
``reasonable cost'' so that mine operators can properly determine
whether they are complying with the requirements of this part when
charging for additional copies. The Agency expects mine operators to
charge reasonable copying costs and labor rates which are generally
applicable in their geographical locations for the same or similar
services and which may vary somewhat from place to place. Therefore,
the final rule does not adopt this comment.
Paragraph (b)(1) is similar to proposed Sec. 62.210(a), requiring
the mine operator to transfer all records required to be maintained by
this part, or copies of them, to a successor mine operator who must
maintain the records for the length of time required by this part.
Several commenters supported the provision as proposed. One commenter
stated that MSHA should clarify that this requirement does not apply to
a successor operator hiring a miner who has never worked at that mine
location. MSHA considers paragraph (b)(1) clear in stating that the
mine operator must transfer all records required to be maintained by
this part to a successor mine operator who then becomes responsible for
maintaining them for the period required.
Paragraph (b)(2) is identical to proposed Sec. 62.210(b), requiring
the successor operator to use the baseline audiogram, or revised
baseline audiogram as appropriate, obtained by the original operator
for determining the existence of a standard threshold shift or
reportable hearing loss. MSHA believes that requiring successor mine
operators to maintain the prior baseline audiogram will provide miners
with the greatest possible degree of protection. Otherwise, if a new
baseline were allowed to be established by the arrival of a successor
mine operator, the record of any existing hearing loss would be wiped
out and reporting or corrective action postponed. The Agency did not
receive any comments on this provision, and paragraph (b)(2) is adopted
as proposed.
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List of Subjects
30 CFR Parts 56 and 57
Metals, Mine safety and health, Noise control.
30 CFR Part 62
Mine safety and health, Noise control.
30 CFR Parts 70 and 71
Coal, Mine safety and health, Noise control.
Dated: August 30, 1999.
J. Davitt McAteer,
Assistant Secretary for Mine Safety and Health.
Accordingly, Chapter I of Title 30 of the Code of Federal
Regulations is amended as follows:
PART 56--[AMENDED]
1. The authority citation for part 56 continues to read as follows:
Authority: 30 U.S.C. 811.
Sec. 56.5050 [Removed]
2. Section 56.5050 and the undesignated center heading preceding it
are removed.
PART 57--[AMENDED]
3. The authority citation for part 57 continues to read as follows:
Authority: 30 U.S.C. 811.
Sec. 57.5050 [Removed]
4. Section 57.5050 and the undesignated center heading preceding it
are removed.
PART 70--[AMENDED]
5. The authority citation for part 70 continues to read as follows:
Authority: 30 U.S.C. 811 and 961.
[[Page 49630]]
Subpart F--[Removed]
6. Subpart F (Secs. 70.500 through 70.511) is removed.
PART 71--[AMENDED]
7. The authority citation for part 71 continues to read as follows:
Authority: 30 U.S.C. 811, 951, 957, 961.
Supbart I--[Removed]
8. Subpart I (Secs. 71.800 through 71.805) is removed.
Subchapters M and N--[Redsignated]
9. Subchapter M is redesignated as Subchapter I, Subchapter N is
redesignated as Subchapter K, and Subchapter N is reserved.
10. A new Subchapter M is added, ``Uniform Mine Health
Regulations.''
11. A new part 62 is added to new Subchapter M to read as follows:
PART 62--OCCUPATIONAL NOISE EXPOSURE
Sec.
62.100 Purpose and scope; effective date
62.101 Definitions
62.110 Noise exposure assessment
62.120 Action level
62.130 Permissible exposure level
62.140 Dual hearing protection level
62.150 Hearing conservation program
62.160 Hearing protectors
62.170 Audiometric testing
62.171 Audiometric test procedures
62.172 Evaluation of audiograms
62.173 Follow-up evaluation when an audiogram is invalid
62.174 Follow-up corrective measures when a standard threshold
shift is detected
62.175 Notification of results; reporting requirements
62.180 Training
62.190 Records
Appendix to part 62
Authority: 30 U.S.C. 811.
Sec. 62.100 Purpose and scope; effective date.
The purpose of these standards is to prevent the occurrence and
reduce the progression of occupational noise-induced hearing loss among
miners. This part sets forth mandatory health standards for each
surface and underground metal, nonmetal, and coal mine subject to the
Federal Mine Safety and Health Act of 1977. The provisions of this part
become effective September 13, 2000.
Sec. 62.101 Definitions.
The following definitions apply in this part:
Access. The right to examine and copy records.
Action level. An 8-hour time-weighted average sound level
(TWA8) of 85 dBA, or equivalently a dose of 50%, integrating
all sound levels from 80 dBA to at least 130 dBA.
Audiologist. A professional, specializing in the study and
rehabilitation of hearing, who is certified by the American Speech-
Language-Hearing Association (ASHA) or licensed by a state board of
examiners.
Baseline audiogram. The audiogram recorded in accordance with
Sec. 62.170(a) of this part against which subsequent audiograms are
compared to determine the extent of hearing loss.
Criterion level. The sound level which if constantly applied for 8
hours results in a dose of 100% of that permitted by the standard.
Decibel (dB). A unit of measure of sound pressure levels, defined
in one of two ways, depending upon the use:
(1) For measuring sound pressure levels, the decibel is 20 times
the common logarithm of the ratio of the measured sound pressure to the
standard reference sound pressure of 20 micropascals (Pa),
which is the threshold of normal hearing sensitivity at 1000 Hertz
(Hz).
(2) For measuring hearing threshold levels, the decibel is the
difference between audiometric zero (reference pressure equal to 0
hearing threshold level) and the threshold of hearing of the individual
being tested at each test frequency.
Dual Hearing Protection Level. A TWA8 of 105 dBA, or
equivalently, a dose of 800% of that permitted by the standard,
integrating all sound levels from 90 dBA to at least 140 dBA.
Exchange rate. The amount of increase in sound level, in decibels,
which would require halving of the allowable exposure time to maintain
the same noise dose. For the purposes of this part, the exchange rate
is 5 decibels (5 dB).
Hearing protector. Any device or material, capable of being worn on
the head or in the ear canal, sold wholly or in part on the basis of
its ability to reduce the level of sound entering the ear, and which
has a scientifically accepted indicator of noise reduction value.
Hertz (Hz). Unit of measurement of frequency numerically equal to
cycles per second.
Medical pathology. A condition or disease affecting the ear.
Miner's designee. Any individual or organization to whom a miner
gives written authorization to exercise a right of access to records.
Qualified technician. A technician who has been certified by the
Council for Accreditation in Occupational Hearing Conservation (CAOHC),
or by another recognized organization offering equivalent
certification.
Permissible exposure level. A TWA8 of 90 dBA or
equivalently a dose of 100% of that permitted by the standard,
integrating all sound levels from 90 dBA to at least 140 dBA.
Reportable hearing loss. A change in hearing sensitivity for the
worse, relative to the miner's baseline audiogram, or the miner's
revised baseline audiogram where one has been established in accordance
with Sec. 62.170(c)(2), of an average of 25 dB or more at 2000, 3000,
and 4000 Hz in either ear.
Revised baseline audiogram. An annual audiogram designated to be
used in lieu of a miner's original baseline audiogram in measuring
changes in hearing sensitivity as a result of the circumstances set
forth in Secs. 62.170(c)(1) or 62.170(c)(2) of this part.
Sound level. The sound pressure level in decibels measured using
the A-weighting network and a slow response, expressed in the unit dBA.
Standard threshold shift. A change in hearing sensitivity for the
worse relative to the miner's baseline audiogram, or relative to the
most recent revised baseline audiogram where one has been established,
of an average of 10 dB or more at 2000, 3000, and 4000 Hz in either
ear.
Time-weighted average-8 hour (TWA8). The sound level
which, if constant over 8 hours, would result in the same noise dose as
is measured.
Sec. 62.110 Noise exposure assessment.
(a) The mine operator must establish a system of monitoring that
evaluates each miner's noise exposure sufficiently to determine
continuing compliance with this part.
(b) The mine operator must determine a miner's noise dose (D, in
percent) by using a noise dosimeter or by computing the formula:
D=100(C1/T1+C2/T2+ . . . .
+Cn/Tn), where Cn is the total time the miner is
exposed at a specified sound level, and Tn is the reference
duration of exposure at that sound level shown in Table 62-1.
(1) The mine operator must use Table 62-2 when converting from dose
readings to equivalent TWA8 readings.
(2) A miner's noise dose determination must:
(i) Be made without adjustment for the use of any hearing
protector;
(ii) Integrate all sound levels over the appropriate range;
[[Page 49631]]
(iii) Reflect the miner's full work shift;
(iv) Use a 90-dB criterion level and a 5-dB exchange rate; and
(v) Use the A-weighting and slow response instrument settings.
(c) Observation of monitoring. The mine operator must provide
affected miners and their representatives with an opportunity to
observe noise exposure monitoring required by this section and must
give prior notice of the date and time of intended exposure monitoring
to affected miners and their representatives.
(d) Miner notification. The mine operator must notify a miner of
his or her exposure when the miner's exposure is determined to equal or
exceed the action level, exceed the permissible exposure level, or
exceed the dual hearing protection level, provided the mine operator
has not notified the miner of an exposure at such level within the
prior 12 months. The mine operator must base the notification on an
exposure evaluation conducted either by the mine operator or by an
authorized representative of the Secretary of Labor. The mine operator
must notify the miner in writing within 15 calendar days of:
(1) The exposure determination; and (2) the corrective action being
taken.
(e) The mine operator must maintain a copy of any such miner
notification, or a list on which the relevant information about that
miner's notice is recorded, for the duration of the affected miner's
exposure at or above the action level and for at least 6 months
thereafter.
Sec. 62.120 Action level.
If during any work shift a miner's noise exposure equals or exceeds
the action level the mine operator must enroll the miner in a hearing
conservation program that complies with Sec. 62.150 of this part.
Sec. 62.130 Permissible exposure level.
(a) The mine operator must assure that no miner is exposed during
any work shift to noise that exceeds the permissible exposure level. If
during any work shift a miner's noise exposure exceeds the permissible
exposure level, the mine operator must use all feasible engineering and
administrative controls to reduce the miner's noise exposure to the
permissible exposure level, and enroll the miner in a hearing
conservation program that complies with Sec. 62.150 of this part. When
a mine operator uses administrative controls to reduce a miner's
exposure, the mine operator must post the procedures for such controls
on the mine bulletin board and provide a copy to the affected miner.
(b) If a miner's noise exposure continues to exceed the permissible
exposure level despite the use of all feasible engineering and
administrative controls, the mine operator must continue to use the
engineering and administrative controls to reduce the miner's noise
exposure to as low a level as is feasible.
(c) The mine operator must assure that no miner is exposed at any
time to sound levels exceeding 115 dBA, as determined without
adjustment for the use of any hearing protector.
Sec. 62.140 Dual hearing protection level.
If during any work shift a miner's noise exposure exceeds the dual
hearing protection level, the mine operator must, in addition to the
actions required for noise exposures that exceed the permissible
exposure level, provide and ensure the concurrent use of both an ear
plug and an ear muff type hearing protector. The following table sets
out mine operator actions under MSHA's noise standard.
----------------------------------------------------------------------------------------------------------------
Provision Condition Action required by the mine operator
----------------------------------------------------------------------------------------------------------------
Sec. 62.120....................... Miner's noise exposure is None.
less than the action level.
Sec. 62.120....................... Miner's exposure equals or Operator enrolls the miner in hearing
exceeds the action level, conservation program (HCP) which includes (1)
but does not exceed the a system of monitoring, (2) voluntary, with
permissible exposure level two exceptions, use of operator-provided
(PEL). hearing protectors, (3) voluntary audiometric
testing, (4) training, and (5) record
keeping.
Sec. 62.130....................... Miner's exposure exceeds Operator uses/continues to use all feasible
the PEL. engineering and administrative controls to
reduce exposure to PEL; enrolls the miner in
a HCP including ensured use of operator-
provided hearing protectors; posts
administrative controls and provides copy to
affected miner; must never permit a miner to
be exposed to sound levels exceeding 115 dBA.
Sec. 62.140....................... Miner's exposure exceeds Operator enrolls the miner in a HCP, continues
the dual hearing to meet all the requirements of Sec. 62.130,
protection level. ensures concurrent use of earplug and
earmuff.
----------------------------------------------------------------------------------------------------------------
Sec. 62.150 Hearing conservation program.
A hearing conservation program established under this part must
include:
(a) A system of monitoring under Sec. 62.110 of this part;
(b) The provision and use of hearing protectors under Sec. 62.160
of this part;
(c) Audiometric testing under Secs. 62.170 through 62.175 of this
part;
(d) Training under Sec. 62.180 of this part; and
(e) Recordkeeping under Sec. 62.190 of this part.
Sec. 62.160 Hearing protectors.
(a) A mine operator must provide a hearing protector to a miner
whose noise exposure equals or exceeds the action level under
Sec. 62.120 of this part. In addition, the mine operator must:
(1) Train the miner in accordance with Sec. 62.180 of this part;
(2) Allow the miner to choose a hearing protector from at least two
muff types and two plug types, and in the event dual hearing protectors
are required, to choose one of each type;
(3) Ensure that the hearing protector is in good condition and is
fitted and maintained in accordance with the manufacturer's
instructions;
(4) Provide the hearing protector and necessary replacements at no
cost to the miner; and
(5) Allow the miner to choose a different hearing protector(s), if
wearing the selected hearing protector(s) is subsequently precluded due
to medical pathology of the ear.
(b) The mine operator must ensure, after satisfying the
requirements of paragraph (a) of this section, that a miner wears a
hearing protector whenever the miner's noise exposure exceeds the
permissible exposure level before the implementation of engineering and
administrative controls, or if the miner's noise exposure continues to
exceed the permissible exposure level despite the use of all feasible
engineering and administrative controls.
(c) The mine operator must ensure, after satisfying the
requirements of paragraph (a) of this section, that a miner wears a
hearing protector when
[[Page 49632]]
the miner's noise exposure is at or above the action level, if:
(1) The miner has incurred a standard threshold shift; or
(2) More than 6 months will pass before the miner can take a
baseline audiogram.
Sec. 62.170 Audiometric testing.
The mine operator must provide audiometric tests to satisfy the
requirements of this part at no cost to the miner. A physician or an
audiologist, or a qualified technician under the direction or
supervision of a physician or an audiologist must conduct the tests.
(a) Baseline audiogram. The mine operator must offer miners the
opportunity for audiometric testing of the miner's hearing sensitivity
for the purpose of establishing a valid baseline audiogram to compare
with subsequent annual audiograms. The mine operator may use an
existing audiogram of the miner's hearing sensitivity as the baseline
audiogram if it meets the audiometric testing requirements of
Sec. 62.171 of this part.
(1) The mine operator must offer and provide within 6 months of
enrolling the miner in a hearing conservation program, audiometric
testing which results in a valid baseline audiogram, or offer and
provide the testing within 12 months where the operator uses mobile
test vans to do the testing.
(2) The mine operator must notify the miner to avoid high levels of
noise for at least 14 hours immediately preceding the baseline
audiogram. The mine operator must not expose the miner to workplace
noise for the 14-hour quiet period before conducting the audiometric
testing to determine a baseline audiogram. The operator may substitute
the use of hearing protectors for this quiet period.
(3) The mine operator must not establish a new baseline audiogram
or a new revised baseline audiogram, where one has been established,
due to changes in enrollment status in the hearing conservation
program. The mine operator may establish a new baseline or revised
baseline audiogram for a miner who is away from the mine for more than
6 consecutive months.
(b) Annual audiogram. After the baseline audiogram is established,
the mine operator must continue to offer subsequent audiometric tests
at intervals not exceeding 12 months for as long as the miner remains
in the hearing conservation program.
(c) Revised baseline audiogram. An annual audiogram must be deemed
to be a revised baseline audiogram when, in the judgment of the
physician or audiologist:
(1) A standard threshold shift revealed by the audiogram is
permanent; or (2) The hearing threshold shown in the annual audiogram
indicates significant improvement over the baseline audiogram.
Sec. 62.171 Audiometric test procedures.
(a) All audiometric testing under this part must be conducted in
accordance with scientifically validated procedures. Audiometric tests
must be pure tone, air conduction, hearing threshold examinations, with
test frequencies including 500, 1000, 2000, 3000, 4000, and 6000 Hz.
Each ear must be tested separately.
(b) The mine operator must compile an audiometric test record for
each miner tested. The record must include:
(1) Name and job classification of the miner tested;
(2) A copy of all of the miner's audiograms conducted under this
part;
(3) Evidence that the audiograms were conducted in accordance with
paragraph (a) of this section;
(4) Any exposure determination for the miner conducted in
accordance with Sec. 62.110 of this part; and
(5) The results of follow-up examination(s), if any.
(c) The operator must maintain audiometric test records for the
duration of the affected miner's employment, plus at least 6 months,
and make the records available for inspection by an authorized
representative of the Secretary of Labor.
Sec. 62.172 Evaluation of audiograms.
(a) The mine operator must:
(1) Inform persons evaluating audiograms of the requirements of
this part and provide those persons with a copy of the miner's
audiometric test records;
(2) Have a physician or an audiologist, or a qualified technician
who is under the direction or supervision of a physician or
audiologist:
(i) Determine if the audiogram is valid; and
(ii) Determine if a standard threshold shift or a reportable
hearing loss, as defined in this part, has occurred.
(3) Instruct the physician, audiologist, or qualified technician
not to reveal to the mine operator, without the written consent of the
miner, any specific findings or diagnoses unrelated to the miner's
hearing loss due to occupational noise or the wearing of hearing
protectors; and
(4) Obtain the results and the interpretation of the results of
audiograms conducted under this part within 30 calendar days of
conducting the audiogram.
(b)(1) The mine operator must provide an audiometric retest within
30 calendar days of receiving a determination that an audiogram is
invalid, provided any medical pathology has improved to the point that
a valid audiogram may be obtained.
(2) If an annual audiogram demonstrates that the miner has incurred
a standard threshold shift or reportable hearing loss, the mine
operator may provide one retest within 30 calendar days of receiving
the results of the audiogram and may use the results of the retest as
the annual audiogram.
(c) In determining whether a standard threshold shift or reportable
hearing loss has occurred, allowance may be made for the contribution
of aging (presbycusis) to the change in hearing level. The baseline, or
the revised baseline as appropriate, and the annual audiograms used in
making the determination should be adjusted according to the following
procedure:
(1) Determine from Tables 62-3 or 62-4 the age correction values
for the miner by:
(i) Finding the age at which the baseline audiogram or revised
baseline audiogram, as appropriate, was taken, and recording the
corresponding values of age corrections at 2000, 3000, and 4000 Hz;
(ii) Finding the age at which the most recent annual audiogram was
obtained and recording the corresponding values of age corrections at
2000, 3000, and 4000 Hz; and
(iii) Subtracting the values determined in paragraph (c)(1)(i) of
this section from the values determined in paragraph (c)(1)(ii) of this
section. The differences calculated represent that portion of the
change in hearing that may be due to aging.
(2) Subtract the values determined in paragraph (c)(1)(iii) of this
section from the hearing threshold levels found in the annual audiogram
to obtain the adjusted annual audiogram hearing threshold levels.
(3) Subtract the hearing threshold levels in the baseline audiogram
or revised baseline audiogram from the adjusted annual audiogram
hearing threshold levels determined in paragraph (c)(2) of this section
to obtain the age-corrected threshold shifts.
Sec. 62.173 Follow-up evaluation when an audiogram is invalid.
(a) If a valid audiogram cannot be obtained due to a suspected
medical pathology of the ear that the physician or audiologist believes
was caused or
[[Page 49633]]
aggravated by the miner's occupational exposure to noise or the wearing
of hearing protectors, the mine operator must refer the miner for a
clinical-audiological evaluation or an otological examination, as
appropriate, at no cost to the miner.
(b) If a valid audiogram cannot be obtained due to a suspected
medical pathology of the ear that the physician or audiologist
concludes is unrelated to the miner's occupational exposure to noise or
the wearing of hearing protectors, the mine operator must instruct the
physician or audiologist to inform the miner of the need for an
otological examination.
(c) The mine operator must instruct the physician, audiologist, or
qualified technician not to reveal to the mine operator, without the
written consent of the miner, any specific findings or diagnoses
unrelated to the miner's occupational exposure to noise or the wearing
of hearing protectors.
Sec. 62.174 Follow-up corrective measures when a standard threshold
shift is detected.
The mine operator must, within 30 calendar days of receiving
evidence or confirmation of a standard threshold shift, unless a
physician or audiologist determines the standard threshold shift is
neither work-related nor aggravated by occupational noise exposure:
(a) Retrain the miner, including the instruction required by
Sec. 62.180 of this part;
(b) Provide the miner with the opportunity to select a hearing
protector, or a different hearing protector if the miner has previously
selected a hearing protector, from among those offered by the mine
operator in accordance with Sec. 62.160 of this part; and
(c) Review the effectiveness of any engineering and administrative
controls to identify and correct any deficiencies.
Sec. 62.175 Notification of results; reporting requirements.
(a) The mine operator must, within 10 working days of receiving the
results of an audiogram, or receiving the results of a follow-up
evaluation required under Sec. 62.173 of this part, notify the miner in
writing of:
(1) The results and interpretation of the audiometric test,
including any finding of a standard threshold shift or reportable
hearing loss; and
(2) The need and reasons for any further testing or evaluation, if
applicable.
(b) When evaluation of the audiogram shows that a miner has
incurred a reportable hearing loss as defined in this part, the mine
operator must report such loss to MSHA as a noise-induced hearing loss
in accordance with part 50 of this title, unless a physician or
audiologist has determined that the loss is neither work-related nor
aggravated by occupational noise exposure.
Sec. 62.180 Training.
(a) The mine operator must, within 30 days of a miner's enrollment
into a hearing conservation program, provide the miner with training.
The mine operator must give training every 12 months thereafter if the
miner's noise exposure continues to equal or exceed the action level.
Training must include:
(1) The effects of noise on hearing;
(2) The purpose and value of wearing hearing protectors;
(3) The advantages and disadvantages of the hearing protectors to
be offered;
(4) The various types of hearing protectors offered by the mine
operator and the care, fitting, and use of each type;
(5) The general requirements of this part;
(6) The mine operator's and miner's respective tasks in maintaining
mine noise controls; and
(7) The purpose and value of audiometric testing and a summary of
the procedures.
(b) The mine operator must certify the date and type of training
given each miner, and maintain the miner's most recent certification
for as long as the miner is enrolled in the hearing conservation
program and for at least 6 months thereafter.
Sec. 62.190 Records.
(a) The authorized representatives of the Secretaries of Labor and
Health and Human Services must have access to all records required
under this part. Upon written request, the mine operator must provide,
within 15 calendar days of the request, access to records to:
(1) The miner, or with the miner's written consent, the miner's
designee, for all records that the mine operator must maintain for that
individual miner under this part;
(2) Any representative of miners designated under part 40 of this
title, to training certifications compiled under Sec. 62.180(b) of this
part and to any notice of exposure determination under Sec. 62.110(d)
of this part, for the miners whom he or she represents; and
(3) Any former miner, for records which indicate his or her own
exposure.
(b) When a person with access to records under paragraphs (a)(1),
(a)(2), or (a)(3) of this section requests a copy of a record, the mine
operator must provide the first copy of such record at no cost to that
person, and any additional copies requested by that person at
reasonable cost.
(c) Transfer of records. (1) The mine operator must transfer all
records required to be maintained by this part, or a copy thereof, to a
successor mine operator who must maintain the records for the time
period required by this part.
(2) The successor mine operator must use the baseline audiogram, or
revised baseline audiogram, as appropriate, obtained by the original
mine operator to determine the existence of a standard threshold shift
or reportable hearing loss.
Appendix to Part 62
Table 62-1.--Reference Duration
------------------------------------------------------------------------
dBA T (hours)
------------------------------------------------------------------------
80........................................................ 32.0
85........................................................ 16.0
86........................................................ 13.9
87........................................................ 12.1
88........................................................ 10.6
89........................................................ 9.2
90........................................................ 8.0
91........................................................ 7.0
92........................................................ 6.1
93........................................................ 5.3
94........................................................ 4.6
95........................................................ 4.0
96........................................................ 3.5
97........................................................ 3.0
98........................................................ 2.6
99........................................................ 2.3
100....................................................... 2.0
101....................................................... 1.7
102....................................................... 1.5
103....................................................... 1.3
104....................................................... 1.1
105....................................................... 1.0
106....................................................... 0.87
107....................................................... 0.76
108....................................................... 0.66
109....................................................... 0.57
110....................................................... 0.50
111....................................................... 0.44
112....................................................... 0.38
113....................................................... 0.33
114....................................................... 0.29
115....................................................... 0.25
------------------------------------------------------------------------
At no time shall any excursion exceed 115 dBA. For any value, the
reference duration (T) in hours is computed by: T = 8/2(L-90)5 where L
is the measured A-weighted, slow-response sound pressure level.
Table 62-2.--``Dose''/TWA8 Equivalent
------------------------------------------------------------------------
Dose (percent) TWA8
------------------------------------------------------------------------
25............................................................. 80
29............................................................. 81
33............................................................. 82
38............................................................. 83
44............................................................. 84
50............................................................. 85
57............................................................. 86
66............................................................. 87
[[Page 49634]]
76............................................................. 88
87............................................................. 89
100............................................................ 90
115............................................................ 91
132............................................................ 92
152............................................................ 93
174............................................................ 94
200............................................................ 95
230............................................................ 96
264............................................................ 97
303............................................................ 98
350............................................................ 99
400............................................................ 100
460............................................................ 101
530............................................................ 102
610............................................................ 103
700............................................................ 104
800............................................................ 105
920............................................................ 106
1056........................................................... 107
1213........................................................... 108
1393........................................................... 109
1600........................................................... 110
1838........................................................... 111
2111........................................................... 112
2425........................................................... 113
2786........................................................... 114
3200........................................................... 115
------------------------------------------------------------------------
Interpolate between the values found in this Table, or extend the Table,
by using the formula: TWA8 = 16.61 log10 (D/100) + 90.
Table 62-3.--Age Correction Value in Decibels for Males (Selected
Frequencies)
------------------------------------------------------------------------
kHz
Age (years) -----------------------
2 3 4
------------------------------------------------------------------------
20 or less...................................... 3 4 5
21.............................................. 3 4 5
22.............................................. 3 4 5
23.............................................. 3 4 6
24.............................................. 3 5 6
25.............................................. 3 5 7
26.............................................. 4 5 7
27.............................................. 4 6 7
28.............................................. 4 6 8
29.............................................. 4 6 8
30.............................................. 4 6 9
31.............................................. 4 7 9
32.............................................. 5 7 10
33.............................................. 5 7 10
34.............................................. 5 8 11
35.............................................. 5 8 11
36.............................................. 5 9 12
37.............................................. 6 9 12
38.............................................. 6 9 13
39.............................................. 6 10 14
40.............................................. 6 10 14
41.............................................. 6 10 14
42.............................................. 7 11 16
43.............................................. 7 12 16
44.............................................. 7 12 17
45.............................................. 7 13 18
46.............................................. 8 13 19
47.............................................. 8 14 19
48.............................................. 8 14 20
49.............................................. 9 15 21
50.............................................. 9 16 22
51.............................................. 9 16 23
52.............................................. 10 17 24
53.............................................. 10 18 25
54.............................................. 10 18 26
55.............................................. 11 19 27
56.............................................. 11 20 28
57.............................................. 11 21 29
58.............................................. 12 22 31
59.............................................. 12 22 32
60 or more...................................... 13 23 33
------------------------------------------------------------------------
Table 62-4.--Age Correction Value in Decibels for Females (Selected
Frequencies)
------------------------------------------------------------------------
kHz
Age (years) -----------------------
2 3 4
------------------------------------------------------------------------
20 or less...................................... 4 3 3
21.............................................. 4 4 3
22.............................................. 4 4 4
23.............................................. 5 4 4
24.............................................. 5 4 4
25.............................................. 5 4 4
26.............................................. 5 5 4
27.............................................. 5 5 5
28.............................................. 5 5 5
29.............................................. 5 5 5
30.............................................. 6 5 5
31.............................................. 6 6 5
32.............................................. 6 6 6
33.............................................. 6 6 6
34.............................................. 6 6 6
35.............................................. 6 7 7
36.............................................. 7 7 7
37.............................................. 7 7 7
38.............................................. 7 7 7
39.............................................. 7 8 8
40.............................................. 7 8 8
41.............................................. 8 8 8
42.............................................. 8 9 9
43.............................................. 8 9 9
44.............................................. 8 9 9
45.............................................. 8 10 10
46.............................................. 9 10 10
47.............................................. 9 10 11
48.............................................. 9 11 11
49.............................................. 9 11 11
50.............................................. 10 11 12
51.............................................. 10 11 12
52.............................................. 10 12 13
53.............................................. 10 13 13
54.............................................. 11 13 14
55.............................................. 11 14 14
56.............................................. 11 14 15
57.............................................. 11 15 15
58.............................................. 12 15 16
59.............................................. 12 16 16
60 or more...................................... 12 16 17
------------------------------------------------------------------------
[FR Doc. 99-22964 Filed 9-7-99; 8:45 am]
BILLING CODE 4510-33-P
